Cyclin-dependent kinase complex (CDK complex) (CDK complex)

The Cyclin-dependent kinase (CDK) complex is a fundamental cell cycle regulatory complex composed of a catalytic kinase subunit (CDK) and a regulatory cyclin subunit. These complexes act as master switches that drive the cell through various phases of the cell cycle (G1, S, G2, and M) by phosphorylating key substrates, most notably the Retinoblastoma (Rb) protein. In many cancers, the regulation of these complexes is disrupted—often through the overexpression of cyclins or the loss of endogenous CDK inhibitors like p16—leading to uncontrolled cell proliferation. Consequently, the CDK-Cyclin complexes, particularly the CDK4/6-Cyclin D complex, have become major therapeutic targets. Selective inhibitors such as palbociclib and ribociclib are widely used in the treatment of hormone receptor-positive, HER2-negative metastatic breast cancer. These drugs work by binding to the ATP-binding site of the CDK, preventing the formation of an active complex and inducing cell cycle arrest in the G1 phase. While "cell cycle regulatory complex" is a broad term that can also encompass other entities like the Anaphase-Promoting Complex/Cyclosome (APC/C) or the DREAM complex, it is most frequently used in a clinical context to refer to the CDK-Cyclin complexes targeted by modern oncology therapeutics.

Other names

Cell cycle regulatory complexCDK-Cyclin complexCyclin-CDK complexCyclin-dependent kinase holoenzyme

Inhibition of the catalytic activity of cyclin-dependent kinases (CDKs) within the CDK-Cyclin complex, preventing the phosphorylation of downstream targets like the retinoblastoma (Rb) protein, thereby inducing cell cycle arrest.