CDK11B (cyclin dependent kinase 11B) is a cell cycle-regulated kinase that plays critical roles in transcriptional regulation and cellular proliferation. The protein is specifically expressed during G2-M phases of the cell cycle and functions as a key regulator of RNA polymerase II activity, phosphorylating serine-2 of the C-terminal domain (CTD) to promote transcriptional processes 1. CDK11B promotes centromeric transcription to maintain chromosome 1 during mitosis, highlighting its importance in proper cell division 21. The kinase demonstrates significant disease relevance across multiple cancer types, with studies showing that cancer cells are addicted to CDK11B expression for proliferation 3. In hepatocellular carcinoma, CDK11B promotes tumor growth and is stabilized by USP22 deubiquitinase activity 4. The protein also contributes to cancer stem cell self-renewal through SPDEF ubiquitination pathways 5. Additionally, CDK11B participates in liver fibrosis pathogenesis, where kinase inhibitors show therapeutic potential 6. Loss-of-function mutations in CDK11B have been identified in rare cancers like sclerosing microcystic adenocarcinoma 7, and the gene shows prognostic significance in osteosarcoma 8. These findings establish CDK11B as a promising therapeutic target across multiple pathological contexts.