Cyclin-dependent kinase (CDK) (CDK)

Cyclin-dependent kinases (CDKs) are a family of serine/threonine kinases that play central roles in regulating the eukaryotic cell cycle and gene transcription (StatPearls, 2023). CDK9, specifically, is a key component of the Positive Transcription Elongation Factor b (P-TEFb) complex, which phosphorylates the C-terminal domain of RNA polymerase II to promote transcriptional elongation of short-lived anti-apoptotic proteins like MCL-1 and oncogenes like MYC (UniProt, 2024). Other members of the family, such as CDK1, CDK2, CDK4, and CDK6, are primarily responsible for orchestrating the transitions between different phases of the cell cycle (PubMed, 2022). Dysregulation or overexpression of CDKs is a hallmark of many cancers, leading to unchecked cell proliferation and resistance to apoptosis (Nature Reviews Cancer, 2021). Consequently, CDKs have become major therapeutic targets; while early pan-CDK inhibitors like flavopiridol faced toxicity challenges due to broad activity, newer generations of drugs focus on selectivity for specific isoforms like CDK4/6 for breast cancer or CDK9 for hematologic malignancies (Journal of Clinical Oncology, 2023). These agents typically act as ATP-competitive inhibitors, triggering cell cycle arrest or rapid apoptosis in sensitive tumor cells (PubChem, 2024). Common side effects of these agents include myelosuppression and gastrointestinal distress, reflecting the role of CDKs in normal regenerative tissues.

Other names

CDK9 and other CDKsCell division protein kinaseSerine/threonine-protein kinasePITALRECDC2Cyc-dependent kinase

Inhibition of the ATP-binding pocket of cyclin-dependent kinases, preventing the phosphorylation of downstream substrates such as the Retinoblastoma (Rb) protein or the C-terminal domain of RNA polymerase II, thereby inducing cell cycle arrest or inhibiting transcriptional elongation of pro-survival genes.