CWC15 is a conserved spliceosomal protein that functions as an integral component of the PRP19-CDC5L complex and the NineTeen Complex (NTC), which are essential for pre-mRNA splicing activation 1. As part of the spliceosomal machinery, CWC15 is required for efficient splicing of both U2-type and U12-type introns 1. Beyond splicing, CWC15 has emerged as a multifunctional regulator: it promotes TREX occupancy and facilitates the interaction between the Prp19C complex and RNA polymerase II, thereby supporting transcription elongation 2. CWC15 also positively regulates miRNA biogenesis by binding MIR gene promoters, promoting pri-miRNA transcription, and interacting with microprocessor components to enhance pri-miRNA processing 3. Developmentally, CWC15 is essential for proper embryogenesis and female gametophyte development in plants, with cwc15 mutations causing embryonic lethality 1. Clinically, CWC15 was identified as one of eight splicing factors significantly associated with overall survival in ovarian cancer patients, indicating potential prognostic relevance 4. Notably, genetic studies suggest CWC15 exhibits an inverse relationship with inflammatory bowel disease susceptibility, with epithelial cells identified as a key cellular source 5. The protein's central role in splicing regulation and emerging functions in transcription and RNA processing make it a potential therapeutic target in cancer and inflammatory disorders.