Property Summary

NCBI Gene PubMed Count 91
PubMed Score 116.63
PubTator Score 109.81

Knowledge Summary

Patent

No data available

Expression

  Differential Expression (7)

Disease log2 FC p
malignant mesothelioma -2.000 1.9e-06
osteosarcoma -2.568 4.9e-06
atypical teratoid / rhabdoid tumor 1.500 5.3e-07
group 3 medulloblastoma 1.500 2.4e-04
subependymal giant cell astrocytoma 1.554 2.6e-03
non-inflammatory breast cancer -1.200 1.9e-03
ovarian cancer -1.200 2.4e-06

 GWAS Trait (1)

Gene RIF (72)

PMID Text
26410533 PKM2 interacts with DDB2 and reduces cell survival upon UV irradiation.
26263968 the release of NER components such as DNA damage binding protein 2 (DDB2) and Xeroderma Pigmentosum complementation group C protein (XPC) following oxidative stress might putatively involve their apoptotic role rather than DNA repair function.
26205499 DDB2 is involved in ubiquitination and degradation of PAQR3 in gastric cancer cells.
26187069 data demonstrated that the DDB2 IRES activity was promoted during stress conditions. These results reveal a novel mechanism contributing to DDB2 expression
26130719 DDB2 can bind to the promoter region of NEDD4L and recruit enhancer of zeste homolog 2 histone methyltransferase to repress NEDD4L transcription by enhancing histone H3 lysine 27 trimethylation at the NEDD4L promoter.
25628365 DDB2 is protected by XPC from ubiquitination and degradation in a stochastic manner; thus XPC allows DDB2 to initiate multiple rounds of repair events, thereby contributing to the persistence of cellular DNA repair capacity
24770583 Chromatin retention of DNA damage sensors DDB2 and XPC through loss of p97 segregase causes genotoxicity.
24760829 UV-DDB examines sites on DNA in discrete steps before forming long-lived, nonmotile UV-DDB dimers (DDB1-DDB2)2 at sites of damage.
24753253 study provides new knowledge about the posttranslational regulation of DDB2 and expands the biological functions of protein alpha-N-methylation to DNA repair
24574518 DDB2 protein expression is low in ovarian tumor cells.
24399259 DDB2 rs747650 is involved in androgen metabolism, inflammation processes and scar formation in severe acne.
24335308 DDB2 and a DDB2-ATM feedback loop influence HCMV replication.
24249678 Data support a model wherein DDB1 and DDB2 cooperate to repress Bcl-2 transcription. DDB2 recognizes and binds to the Bcl-2 P1 promoter, and HDAC1 is recruited through the DDB1 subunit associated with DDB2 to deacetylate histone H3K9.
24200966 DDB2 is a PCNA-binding protein and this association is required for DDB2 proteolytic degradation.
23860269 These results suggest that the SUMOylation of DDB2 facilitates CPD repair.
23774208 Knockdown of DDB2-induced IkappaBalpha gene expression restored NF-kappaB activity.
23610444 Results indicate a transcriptional regulatory pathway of DDB2 that is directly linked to the mechanisms that suppress metastasis of colon cancer.
23605047 The 3'untranslated region of DDB2 contains a cis-acting element that affects stability, export and translation of the message
23604128 the data indicate that p53-dependent upregulation of XPC and DDB2 is a key mechanism upon genotoxic stress, whereby melanoma cells acquire resistance towards DNA cross-linking agents.
23422745 DDB2 facilitates ATR and ATM recruitment to the DNA damage site following UV irradiation.
23319653 Data indicate that poly(ADP-ribose) polymerase-1 (PARP-1)collaborates with DNA-binding protein 2 (DDB2) to increase the efficiency of the lesion recognition step of global genomic subpathway of NER (GG-NER).
23109835 DDB2 plays an instrumental role in DNA damage induced ROS accumulation, ROS induced premature senescence and inhibition of skin tumorigenesis.
23045548 data support a model in which poly(ADP-ribosyl)ation of DDB2 suppresses DDB2 ubiquitylation and outline a molecular mechanism for PARP1-mediated regulation of nucleotide excision repair through DDB2 stabilization and recruitment of the chromatin remodeler ALC1
22846800 DDB2 can inhibit cell growth rate in AR-expressing cells (LNCaP) but not in AR-null cells (PC3).
22822215 Findings indicate structural and conformational insights of the DDB1-CUL4A(DDB2) E3 ligase, with significant implications for the regulation and overall organization of the proteins responsible for initiation of nucleotide-excision repair (NER) pathway.
22492724 study reports a new function of DDB2 in modulating chromatin structure at DNA lesions
22039351 DDB2 subunit of UV-DDB associates transiently with the DNA-binding domain of XPC to fine-tune its engagement with CPD lesions
21550341 Studies indicate the modular architecture of DDB1-CUL4 in complex with DDB2, CSA and CDT2 in DNA repair of UV-induced DNA lesions.
21388382 Nucleotide excision repair proteins rapidly accumulate but fail to persist in human xeroderma pigmentosum XP-E (DDB2 mutant) cells.
21107348 Multiple skin cancers in adults are associted with mutations in the XP-E (DDB2) DNA repair gene.
20819778 Observational study of gene-disease association and gene-gene interaction. (HuGE Navigator)
20522537 Observational study of gene-disease association. (HuGE Navigator)
20398405 Damaged DNA-binding protein 2 (DDB2) protects against UV irradiation in human cells and Drosophila
20368362 Data show that XPC and Ku oppositely regulate the ubiquitin ligase activity of DDB2, and that DDB2 complex-mediated ubiquitylation plays a role in recruiting XPA to damaged sites.
20013802 Overexpression of DDB2 enhances the sensitivity of ovarian cancer cells to cisplatin by augmenting cellular apoptosis.
19714462 Observational study of gene-disease association and gene-gene interaction. (HuGE Navigator)
19541625 Results provide evidence for a new regulatory loop involving the NER protein DDB2, Mdm2, and p21(Waf1/Cip1) that is critical in deciding cell fate (apoptosis or arrest) upon DNA damage.
19428372 p53 is primarily protective against ultraviolet rays-induced apoptosis in primary human fibroblasts and this activity of p53 does not require DDB2.
19339246 DDB2 exerts, at least in part, a control of breast cancer cell growth through its negative regulation of constitutive expression of the SOD2 gene.
19237606 Observational study of gene-disease association, gene-gene interaction, and gene-environment interaction. (HuGE Navigator)
19109893 The structure DDB1-DDB2 complex shows the tightly localized probing of the photolesions, combined with proofreading in the photodimer pocket, enables DDB2 to detect lesions refractory to detection by other damage surveillance proteins.
19064572 Observational study and meta-analysis of gene-disease association. (HuGE Navigator)
18936169 Results suggest a model in which UV-dependent degradation of DDB2 is important for the release of DDB1 from continuous association to unrepaired DNA and makes DDB1 available for its other DNA damage response functions.
18806262 p38 MAPK regulates chromatin remodeling as well as DDB2 degradation for facilitating NER factor assembly
18593899 DDB1-CUL4B(DDB2) E3 ligase may have a distinctive function in modifying the chromatin structure at the site of UV lesions to promote efficient NER.
18431487 These findings demonstrate for the first time that DDB2 can play a role as oncogene and may become a promising candidate as a predictive marker in breast cancer.
18089819 p53 determines the switch by regulating ddb2 and DNA double-strand breaks in antineoplastic agent treatment of glioblastoma multiforme.
17967871 provide genetic evidence linking the regulation of p21(Waf1/Cip1) to the nucleotide excision repair activity of DDB2
17855541 HIV-1 Vpr interferes with the interaction of DDB1 and DDB2 in cells
17660462 A nonsense mutation 574CT (R192X) in DDB2 was found in association facial neoplasms in a form of xeroderma pigmentosum.The parents were heterozygous & the patient homozygous.
17630510 Results suggest that the roles of p53 and nucleotide excision repair in the recovery from UV-induced replication are separable and DDB2-independent.
17360488 HIV-1 Vpr interferes with the interaction of DDB1 and DDB2 in cells
17357082 Genome-wide association study of gene-disease association. (HuGE Navigator)
16951172 DDB2 can bind to damaged DNA in vivo as a monomer, whereas Cul4A recruitment to damage sites depends on the fully assembled complex.
16527807 CUL-4A mediates the proteolytic degradation of DDB2 and this degradation event, initiated at the lesion sites, regulates damage recognition by XPC.
16522664 Observational study of gene-disease association and gene-environment interaction. (HuGE Navigator)
16473935 Monoubiquitinated histone H2A in native chromatin coimmunoprecipitates with the endogenous DDB1-CUL4A(DDB2) complex in response to UV irradiation.
16260596 DDB2 has an intrinsic damaged DNA binding activity
16223728 DDB1-DDB2 protein complex recognizes DNA mismatches and lesions
15882621 UV-DDB interacts with XPC physically, and both are polyubiquitylated by the UV-DDB-ubiquitin ligase complex.
15644494 DDB2 regulates TNF signaling-mediated apoptosis via cFLIP and contributes to acquired cross-resistance.
14751237 identification of four DDB2 variants from HeLa cells (D1-D4) that are generated by alternative splicing
14560002 Data suggest that both before and after UV irradiation, DDB2 directly regulates p53 levels, while DDB2 expression is itself regulated by p53.
12944386 DDB2p48 activates the recruitment of XPC to cyclobutane pyrimidine dimers and may be the initial recognition factor in the nucleotide excision repair pathway
12732143 DDB2 and CSA are each integrated into nearly identical complexes via interaction with DDB1
12553360 overexpression of DDB2 in V79 cell potentiates DNA repair and protects cells from UV-induced apoptosis and cytotoxicity.
12496474 BRCA1 upregulates DDB2, with some evidence that p53 is involved in its regulation.
12151405 These findings indicate that hepatitis B virus X protein acts through a pathway that involves a DDB2-independent nuclear function of DDB1 and that this activity will depend on the relative concentration of DDB1 and DDB2 in cells.
12050362 findings substantiate the physical and functional connection between the hepatitis B virus X protein and the DDB1-DDB2 heterodimer, leading to the regulation of the pool of the viral protein
12034848 Sequential binding of UV DNA damage binding factor and degradation of the p48 subunit as early events after UV irradiation
11971958 These results demonstrate direct activation of the human DDB2 gene by p53. The corresponding region in the mouse DDB2 gene shared significant sequence identity with the human gene but was deficient for p53 binding and transcriptional activation.
11852074 These results indicate that DDB2 is a modulator of UV-induced apoptosis, and that UV resistance can be overcome by inhibition of DDB2

AA Sequence

MAPKKRPETQKTSEIVLRPRNKRSRSPLELEPEAKKLCAKGSGPSRRCDSDCLWVGLAGPQILPPCRSIV      1 - 70
RTLHQHKLGRASWPSVQQGLQQSFLHTLDSYRILQKAAPFDRRATSLAWHPTHPSTVAVGSKGGDIMLWN     71 - 140
FGIKDKPTFIKGIGAGGSITGLKFNPLNTNQFYASSMEGTTRLQDFKGNILRVFASSDTINIWFCSLDVS    141 - 210
ASSRMVVTGDNVGNVILLNMDGKELWNLRMHKKKVTHVALNPCCDWFLATASVDQTVKIWDLRQVRGKAS    211 - 280
FLYSLPHRHPVNAACFSPDGARLLTTDQKSEIRVYSASQWDCPLGLIPHPHRHFQHLTPIKAAWHPRYNL    281 - 350
IVVGRYPDPNFKSCTPYELRTIDVFDGNSGKMMCQLYDPESSGISSLNEFNPMGDTLASAMGYHILIWSQ    351 - 420
EEARTRK                                                                   421 - 427
//

Text Mined References (109)

PMID Year Title
26496610 2015 A human interactome in three quantitative dimensions organized by stoichiometries and abundances.
26410533 2015 Pyruvate kinase M2 interacts with DNA damage-binding protein 2 and reduces cell survival upon UV irradiation.
26263968 2015 Combination of A? Secretion and Oxidative Stress in an Alzheimer-Like Cell Line Leads to the Over-Expression of the Nucleotide Excision Repair Proteins DDB2 and XPC.
26205499 2015 DDB2 is involved in ubiquitination and degradation of PAQR3 and regulates tumorigenesis of gastric cancer cells.
26187069 2015 The 5'-UTR of DDB2 harbors an IRES element and upregulates translation during stress conditions.
26130719 2015 DDB2 modulates TGF-? signal transduction in human ovarian cancer cells by downregulating NEDD4L.
25628365 2015 Functional regulation of the DNA damage-recognition factor DDB2 by ubiquitination and interaction with xeroderma pigmentosum group C protein.
24770583 2014 Chromatin retention of DNA damage sensors DDB2 and XPC through loss of p97 segregase causes genotoxicity.
24760829 2014 Single-molecule analysis reveals human UV-damaged DNA-binding protein (UV-DDB) dimerizes on DNA via multiple kinetic intermediates.
24753253 2014 ?-N-methylation of damaged DNA-binding protein 2 (DDB2) and its function in nucleotide excision repair.
24574518 2014 DDB2 suppresses tumorigenicity by limiting the cancer stem cell population in ovarian cancer.
24399259 2014 Two new susceptibility loci 1q24.2 and 11p11.2 confer risk to severe acne.
24335308 2014 A novel DDB2-ATM feedback loop regulates human cytomegalovirus replication.
24249678 2014 DNA damage-binding complex recruits HDAC1 to repress Bcl-2 transcription in human ovarian cancer cells.
24200966 2014 DDB2 association with PCNA is required for its degradation after UV-induced DNA damage.
23860269 2013 SUMOylation of damaged DNA-binding protein DDB2.
23774208 2013 DDB2: a novel regulator of NF-?B and breast tumor invasion.
23610444 2013 DDB2 suppresses epithelial-to-mesenchymal transition in colon cancer.
23605047 2013 A novel cis-acting element from the 3'UTR of DNA damage-binding protein 2 mRNA links transcriptional and post-transcriptional regulation of gene expression.
23604128 2014 Malignant melanoma cells acquire resistance to DNA interstrand cross-linking chemotherapeutics by p53-triggered upregulation of DDB2/XPC-mediated DNA repair.
23422745 2013 NER initiation factors, DDB2 and XPC, regulate UV radiation response by recruiting ATR and ATM kinases to DNA damage sites.
23319653 2013 Role of poly(ADP-ribose) polymerase-1 in the removal of UV-induced DNA lesions by nucleotide excision repair.
23186163 2013 Toward a comprehensive characterization of a human cancer cell phosphoproteome.
23159851 2012 The deubiquitinating protein USP24 interacts with DDB2 and regulates DDB2 stability.
23109835 2012 Damaged DNA binding protein 2 in reactive oxygen species (ROS) regulation and premature senescence.
23045548 2012 PARP1 promotes nucleotide excision repair through DDB2 stabilization and recruitment of ALC1.
22846800 2012 DDB2 is a novel AR interacting protein and mediates AR ubiquitination/degradation.
22822215 2012 Damaged DNA induced UV-damaged DNA-binding protein (UV-DDB) dimerization and its roles in chromatinized DNA repair.
22492724 2012 DDB2 promotes chromatin decondensation at UV-induced DNA damage.
22334663 2012 Monoubiquitinated histone H2A destabilizes photolesion-containing nucleosomes with concomitant release of UV-damaged DNA-binding protein E3 ligase.
22039351 2011 Regulation of nucleotide excision repair by UV-DDB: prioritization of damage recognition to internucleosomal DNA.
21550341 2011 Detecting UV-lesions in the genome: The modular CRL4 ubiquitin ligase does it best!
21406692 2011 System-wide temporal characterization of the proteome and phosphoproteome of human embryonic stem cell differentiation.
21388382 Nucleotide excision repair proteins rapidly accumulate but fail to persist in human XP-E (DDB2 mutant) cells.
21107348 2011 Multiple skin cancers in adults with mutations in the XP-E (DDB2) DNA repair gene.
20819778 2010 MicroRNA-related genetic variations as predictors for risk of second primary tumor and/or recurrence in patients with early-stage head and neck cancer.
20522537 2010 Variation within DNA repair pathway genes and risk of multiple sclerosis.
20398405 2010 Damaged DNA-binding protein 2 (DDB2) protects against UV irradiation in human cells and Drosophila.
20368362 2010 DDB2 complex-mediated ubiquitylation around DNA damage is oppositely regulated by XPC and Ku and contributes to the recruitment of XPA.
20068231 2010 Quantitative phosphoproteomics reveals widespread full phosphorylation site occupancy during mitosis.
20013802 2010 Overexpression of DDB2 enhances the sensitivity of human ovarian cancer cells to cisplatin by augmenting cellular apoptosis.
19966799 2010 A promiscuous alpha-helical motif anchors viral hijackers and substrate receptors to the CUL4-DDB1 ubiquitin ligase machinery.
19714462 2010 Genetic variation in genes interacting with BRCA1/2 and risk of breast cancer in the Cypriot population.
19690332 2009 Quantitative phosphoproteomic analysis of T cell receptor signaling reveals system-wide modulation of protein-protein interactions.
19541625 2009 DDB2 decides cell fate following DNA damage.
19428372 2009 The anti-apoptotic role for p53 following exposure to ultraviolet light does not involve DDB2.
19339246 2009 Identification of DDB2 protein as a transcriptional regulator of constitutive SOD2 gene expression in human breast cancer cells.
19237606 2009 Genetic polymorphisms in 85 DNA repair genes and bladder cancer risk.
19109893 2008 Structural basis of UV DNA-damage recognition by the DDB1-DDB2 complex.
19064572 2008 Polymorphism in the IL18 gene and epithelial ovarian cancer in non-Hispanic white women.
18936169 2008 Cellular concentrations of DDB2 regulate dynamic binding of DDB1 at UV-induced DNA damage.
18806262 2008 The p38 mitogen-activated protein kinase augments nucleotide excision repair by mediating DDB2 degradation and chromatin relaxation.
18669648 2008 A quantitative atlas of mitotic phosphorylation.
18593899 2008 The cullin 4B-based UV-damaged DNA-binding protein ligase binds to UV-damaged chromatin and ubiquitinates histone H2A.
18431487 2008 Damaged DNA binding protein 2 plays a role in breast cancer cell growth.
18089819 2007 Differential sensitivity of malignant glioma cells to methylating and chloroethylating anticancer drugs: p53 determines the switch by regulating xpc, ddb2, and DNA double-strand breaks.
17967871 2008 The xeroderma pigmentosum group E gene product DDB2 activates nucleotide excision repair by regulating the level of p21Waf1/Cip1.
17660462 2007 Blood-derived gene-expression profiling in unravelling susceptibility to recessive disease.
17635991 2007 Dynamic in vivo interaction of DDB2 E3 ubiquitin ligase with UV-damaged DNA is independent of damage-recognition protein XPC.
17630510 2007 DDB2-independent role for p53 in the recovery from ultraviolet light-induced replication arrest.
17357082 2007 Identification of a novel risk locus for progressive supranuclear palsy by a pooled genomewide scan of 500,288 single-nucleotide polymorphisms.
17207965 2007 hORFeome v3.1: a resource of human open reading frames representing over 10,000 human genes.
17081983 2006 Global, in vivo, and site-specific phosphorylation dynamics in signaling networks.
17079684 2006 DDB1 functions as a linker to recruit receptor WD40 proteins to CUL4-ROC1 ubiquitin ligases.
17041588 2006 CUL4-DDB1 ubiquitin ligase interacts with multiple WD40-repeat proteins and regulates histone methylation.
16964240 2006 Molecular architecture and assembly of the DDB1-CUL4A ubiquitin ligase machinery.
16951172 2006 DNA damage binding protein component DDB1 participates in nucleotide excision repair through DDB2 DNA-binding and cullin 4A ubiquitin ligase activity.
16949367 2006 A family of diverse Cul4-Ddb1-interacting proteins includes Cdt2, which is required for S phase destruction of the replication factor Cdt1.
16713579 2006 A kinase-independent function of c-Abl in promoting proteolytic destruction of damaged DNA binding proteins.
16678110 2006 Histone H3 and H4 ubiquitylation by the CUL4-DDB-ROC1 ubiquitin ligase facilitates cellular response to DNA damage.
16527807 2006 Cullin 4A-mediated proteolysis of DDB2 protein at DNA damage sites regulates in vivo lesion recognition by XPC.
16522664 2006 Polymorphisms in DNA damage binding protein 2 (DDB2) and susceptibility of primary lung cancer in the Chinese: a case-control study.
16473935 2006 The DDB1-CUL4ADDB2 ubiquitin ligase is deficient in xeroderma pigmentosum group E and targets histone H2A at UV-damaged DNA sites.
16344560 2006 Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes.
16260596 2005 Xeroderma pigmentosum complementation group E protein (XPE/DDB2): purification of various complexes of XPE and analyses of their damaged DNA binding and putative DNA repair properties.
16223728 2005 DDB1-DDB2 (xeroderma pigmentosum group E) protein complex recognizes a cyclobutane pyrimidine dimer, mismatches, apurinic/apyrimidinic sites, and compound lesions in DNA.
15882621 2005 UV-induced ubiquitylation of XPC protein mediated by UV-DDB-ubiquitin ligase complex.
15644494 2005 Cross-resistance to death ligand-induced apoptosis in cisplatin-selected HeLa cells associated with overexpression of DDB2 and subsequent induction of cFLIP.
15489334 2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).
14751237 2004 Human DDB2 splicing variants are dominant negative inhibitors of UV-damaged DNA repair.
14702039 2004 Complete sequencing and characterization of 21,243 full-length human cDNAs.
14560002 2003 Impaired regulation of tumor suppressor p53 caused by mutations in the xeroderma pigmentosum DDB2 gene: mutual regulatory interactions between p48(DDB2) and p53.
12944386 2003 In vivo recruitment of XPC to UV-induced cyclobutane pyrimidine dimers by the DDB2 gene product.
12812979 2003 True XP group E patients have a defective UV-damaged DNA binding protein complex and mutations in DDB2 which reveal the functional domains of its p48 product.
12732143 2003 The ubiquitin ligase activity in the DDB2 and CSA complexes is differentially regulated by the COP9 signalosome in response to DNA damage.
12553360 2002 Overexpression of damaged-DNA-binding protein 2 (DDB2) potentiates UV resistance in hamster V79 cells.
12496474 Transactivation of repair genes by BRCA1.
12477932 2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.
12151405 2002 Hepatitis B virus X protein associated with UV-DDB1 induces cell death in the nucleus and is functionally antagonized by UV-DDB2.
12050362 2002 Turnover of hepatitis B virus X protein is regulated by damaged DNA-binding complex.
12034848 2002 Sequential binding of UV DNA damage binding factor and degradation of the p48 subunit as early events after UV irradiation.
11971958 2002 p53 Binds and activates the xeroderma pigmentosum DDB2 gene in humans but not mice.
11705987 2002 DDB accumulates at DNA damage sites immediately after UV irradiation and directly stimulates nucleotide excision repair.
11673459 2001 UV-damaged DNA-binding proteins are targets of CUL-4A-mediated ubiquitination and degradation.
11564863 2001 Human STAGA complex is a chromatin-acetylating transcription coactivator that interacts with pre-mRNA splicing and DNA damage-binding factors in vivo.
11278856 2001 Damaged DNA-binding protein DDB stimulates the excision of cyclobutane pyrimidine dimers in vitro in concert with XPA and replication protein A.
10882109 2000 Xeroderma pigmentosum p48 gene enhances global genomic repair and suppresses UV-induced mutagenesis.
10777491 2000 Nuclear transport of human DDB protein induced by ultraviolet light.
10777490 2000 Human damage-specific DNA-binding protein p48. Characterization of XPE mutations and regulation following UV irradiation.
10583946 1999 Quality control by DNA repair.
10214908 DNA damage recognition during nucleotide excision repair in mammalian cells.
9892649 1999 Expression of the p48 xeroderma pigmentosum gene is p53-dependent and is involved in global genomic repair.
9632823 1998 p48 Activates a UV-damaged-DNA binding factor and is defective in xeroderma pigmentosum group E cells that lack binding activity.
9418871 1998 DDB, a putative DNA repair protein, can function as a transcriptional partner of E2F1.
8798680 1996 Mutations specific to the xeroderma pigmentosum group E Ddb- phenotype.
8602529 1996 A mammalian histone deacetylase related to the yeast transcriptional regulator Rpd3p.
8530102 1995 Chromosomal localization and cDNA cloning of the genes (DDB1 and DDB2) for the p127 and p48 subunits of a human damage-specific DNA binding protein.
8407967 1993 Characterization of a human DNA damage binding protein implicated in xeroderma pigmentosum E.
8350924 1993 A retinoblastoma-binding protein related to a negative regulator of Ras in yeast.