BCAS2 (BCAS2 pre-mRNA processing factor) is a nuclear protein that functions primarily as an essential component of the pre-mRNA splicing machinery. BCAS2 is required for pre-mRNA splicing as part of the activated spliceosome, where it may serve a scaffolding role by contacting other core complex components 1. The protein plays critical roles in alternative splicing regulation, particularly in male germ cells where it controls splicing of spermatogenesis-related genes including Dazl, Ehmt2, and Hmga1 2. BCAS2 exhibits predominant association with 5' splice sites of introns and preference for GA-rich regions 3. Beyond splicing, BCAS2 participates in DNA double-strand break repair by interacting with NBS1 to enhance both non-homologous end joining and homologous recombination pathways 4. The protein also functions as a negative regulator of p53, reducing its transcriptional activity and providing protection against DNA damage-induced apoptosis 5. In prostate cancer, BCAS2 promotes cell proliferation by enhancing androgen receptor mRNA transcription and protein stability 6. BCAS2 amplification occurs in some primary breast cancers and its overexpression correlates with higher Gleason grades and shorter survival in prostate cancer patients 14.