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. Author manuscript; available in PMC: 2016 May 1.
Published in final edited form as: Nat Rev Nephrol. 2015 Feb 3;11(5):264–276. doi: 10.1038/nrneph.2015.3

Figure 6.

Figure 6

Eukaryotic cell-cycle checkpoints. Four phases of cell-cycle progression are seen in eukaryotic cells. Cellular DNA is replicated in the S phase, and cell mitosis occurs in M phase, separated by two gap phases, G1 and G2. Critical checkpoints exist at G1/S and G2/M, where the actions of cyclins, CDKs and their inhibitors determine whether appropriate cell size, DNA replication and integrity exist to allow the initiation of DNA synthesis or the completion of cell division, respectively. Increased numbers of G2/M-arrested cells have been identified as a common feature in models of progressive chronic kidney disease. Abbreviations: CDK, cyclin-dependent kinase; CTGF, connective tissue growth factor; TGF-β, transforming growth factor β.