CDC5L (cell division cycle 5 like) is a multifunctional nuclear protein that plays critical roles in pre-mRNA splicing and cell cycle regulation. As a core component of the PRP19-CDC5L complex, CDC5L is essential for the second catalytic step of pre-mRNA splicing, with immunodepletion studies demonstrating its requirement for splicing product formation 1. The protein contains a Myb-related DNA-binding domain and functions as a transcriptional activator 2. CDC5L participates in genome stability maintenance through its involvement in the NORAD-activated ribonucleoprotein complex 1 (NARC1), which contains topoisomerase I and supports proper chromosome 6 and replication fork progression 3. In cancer biology, CDC5L demonstrates oncogenic properties across multiple tumor types. It promotes gastric cancer progression by interacting with MAPK1 and activating MAPK pathway-mediated homologous recombination 4. In hepatocellular carcinoma, CDC5L inhibits pyroptosis by binding to ELAVL1 and regulating the Caspase 3/GSDME pathway 5. High CDC5L expression correlates with poor prognosis in gliomas and serves as an independent prognostic factor 6. Additionally, CDC5L acts as a downstream effector of EIF4A3 in promoting breast cancer cell proliferation 7.