Cyclin-dependent kinase 6–Cyclin D complex (CDK6–Cyclin D) (CDK6–Cyclin D)

The Cyclin-dependent kinase 6 (CDK6)–Cyclin D complex is a critical regulator of the G1 to S phase transition in the eukaryotic cell cycle (UniProt, P50613). CDK6 is a catalytic subunit that remains inactive until it binds with a regulatory Cyclin D subunit (D1, D2, or D3), forming an active holoenzyme (Klein et al., 2018, Nature Reviews Clinical Oncology). This complex primarily functions by phosphorylating the Retinoblastoma (Rb) protein, which releases E2F transcription factors to initiate the expression of genes required for DNA synthesis (StatPearls, NBK562273). In many cancers, the CDK6–Cyclin D pathway is hyperactivated due to cyclin D amplification or loss of endogenous inhibitors like p16INK4a, leading to uncontrolled cell proliferation (PubMed, PMC6467831). Consequently, this complex has become a major therapeutic target, particularly in hormone receptor-positive breast cancer and various hematological malignancies (DrugBank, DB09073). Small-molecule inhibitors, such as palbociclib and abemaciclib, target the ATP-binding pocket of CDK6 to induce cell cycle arrest (PubMed, PMC5514362). Beyond its role in the cell cycle, CDK6 also plays specialized roles in hematopoiesis and transcriptional regulation, making its selective inhibition a complex but effective strategy in oncology (UniProt, P50613).

Other names

CDK6/Cyclin D complexCyclin D1-CDK6 complexCyclin D2-CDK6 complexCyclin D3-CDK6 complexSerine/threonine-protein kinase 6 complex

Competitive inhibition of the ATP-binding site of CDK6, preventing the phosphorylation of the Retinoblastoma (Rb) protein, which results in cell cycle arrest in the G1 phase (StatPearls, NBK562273).