DNA- and RNA-binding protein, involved in several nuclear processes such as pre-mRNA splicing, apoptosis and transcription regulation. In association with FUBP1 regulates MYC transcription at the P2 promoter through the core-TFIIH basal transcription factor. Acts as a transcriptional repressor through the core-TFIIH basal transcription factor. Represses FUBP1-induced transcriptional activation but not basal transcription. Decreases ERCC3 helicase activity. Does not repress TFIIH-mediated transcription in xeroderma pigmentosum complementation group B (XPB) cells. Is also involved in pre-mRNA splicing. Promotes splicing of an intron with weak 3'-splice site and pyrimidine tract in a cooperative manner with U2AF2. Involved in apoptosis induction when overexpressed in HeLa cells. Isoform 6 failed to repress MYC transcription and inhibited FIR-induced apoptosis in colorectal cancer. Isoform 6 may contribute to tumor progression by enabling increased MYC expression and greater resistance to apoptosis in tumors than in normal cells. Modulates alternative splicing of several mRNAs. Binds to relaxed DNA of active promoter regions. Binds to the pyrimidine tract and 3'-splice site regions of pre-mRNA; binding is enhanced in presence of U2AF2. Binds to Y5 RNA in association with RO60. Binds to poly(U) RNA. Homodimer (PubMed:10606266). Associates with the spliceosome (PubMed:17579712). Found in a complex with RO60 and Y5 RNA (PubMed:10668799). Found in a complex with FUBP1 and far upstream element (FUSE) DNA segment (PubMed:10882074). Interacts directly with ERCC3 (PubMed:11239393). Interacts with CDK7 and GTF2H1 (PubMed:10882074). Interacts with SRSF11/P54 (PubMed:10606266). Does not interact with ERCC3 in xeroderma pigmentosum complementation group B (XPB) cells (PubMed:11239393). Colocalizes partially with RO60. Isoform 2 is expressed in colonic epithelium and colorectal epithelium cancer (at protein level). Isoform 6 is expressed in colorectal epithelial cancer but below detection level in colonic epithelium. Expressed in heart, brain, placenta, lung, liver, skeletal muscle, kidney, pancreas, spleen, thymus, prostate, testis, ovary, small intestine, colon and peripheral blood leukocytes. The third RNA recognition motif, called PUMP domain, is atypical and may rather mediate homodimerization and/or protein-protein interactions. The disease is caused by variants affecting the gene represented in this entry. Does not repress TFIIH-mediated transcription in xeroderma pigmentosum complementation group B (XPB) cells. Belongs to the RRM half pint family.