CHEK2 and cancer: Treatment with CCT241533 (0.05, 0.5, and 5 μM), LY2606368 (0.1, 1, and 10 μM), and PF477736 (0.5 and 5 μμ) had no impact on primordial oocyte survival after radiation at any dose tested (Fig. 6), indicating failure to sufficiently block CHEK2 activity in oocytes although similar doses have been used in cell culture with cancer cell lines.