GDC-0575 is a potent and selective inhibitor of cell cycle checkpoint kinase 1 (Chk1) with an IC50 of 1.2?nM. GDC-0575 specifically binds to and inhibits Chk1; this may result in tumor cells bypassing Chk1-dependent cell cycle arrest in the S and G2/M phases, which permits the cells to undergo DNA repair prior to entry into mitosis.

A potent and selective ATP-competitive inhibitor of CHK2 K5777:N5777with IC50 of 3 nM.

SAR-020106 is a potent, ATP-competitive, and selective CHK1 inhibitor with an IC50 of 13.3 nmol/L on the isolated human enzyme.SAR-020106 is an ATP-competitive, potent, and selective CHK1 inhibitor with an IC(50) of 13.3 nmol/L on the isolated human enzyme. This compound abrogates an etoposide-induced G(2) arrest with an IC(50) of 55 nmol/L in HT29 cells, and significantly enhances the cell killing of gemcitabine and SN38 by 3.0- to 29-fold in several colon tumor lines in vitro and in a p53-dependent fashion.