Cyclin-dependent kinases (CDKs) are protein kinases involved in critical cellular processes, such as cell cycle or transcription, whose activity requires association with specific cyclin subunits.

Tyrosine (Tyr) phosphorylation of p27 by Abl and Src family kinases reduces p27–CDK2 inhibition and transforms p27 from inhibitor to substrate of cyclin–CDK2 complexes. p27 phosphorylation at ...