Cell cycle changes associated with Chk1 inhibition in breast and ovarian cells. Cell cycle profiles of TNBC (A) or ovarian cancer (B) cells were determined by PI staining following treatment with the indicated concentrations of V158411 for 24 hours. C. The fraction of cells with a sub-G1 DNA content was quantitated from the cell cycle profiles following 48 hour incubation. D. MDA-MB-231, MDA-MB-468 or BT474 cells were treated with 1 μM V158411 in the presence or absence of 0.5 μM nocodazole for 24 hours. Protein levels were subsequently assessed by western blotting.