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. 2019 Dec 4;28(1):44–56. doi: 10.1093/annonc/mdw532

Figure 2.

Figure 2

The figure depicts the role of cyclin-dependent kinases 4 and 6 (CDK4/6) in the cell cycle. The normal cell replication processes are represented i.e., G1 first growth period to S DNA replication phase G2 second growth period, and M, which is the mitosis period. Cyclin D1-CDK4/6 inactivates retinoblastoma protein (Rb) through phosphorylation. The latter event allows for cell cycle progression from G1 to S phase. Palbociclib targets cyclin-CDK4/6 complex formation ultimately generating cell cycle arrest. Also low molecular weight cyclin E-cycle dependent kinase 2 (LMW-E-CDK2) complex activation is depicted. When active LMW-E-CDK2 complex is resistant to inhibitory effect of cyclin inhibitors p21 and p27 and promote initiation of S phase. Denaciclib targets CDK2 promoting cell cycles arrest.