Checkpoint kinase 1 (Chk1) regulates S and G2-M phase cell cycle checkpoints in response to DNA damage. PF-477736 is an ATP-competitive inhibitor of Chk1 with a Ki value of 0.49 nM that demonstrates 100-fold selectivity over Chk2. When used in combination with various chemotherapeutics, PF-477736 abrogates DNA damage-induced cell cycle arrest, potentiating the antiproliferative effects of these compounds in tumor cell lines and xenografts.
