Fig. 3.

Knockdown of PARP1-sensitized breast cancer cells toward CHK1 inhibitors. BT474 (A) or HCC38 (B) cells were infected with siRNA control (siSCR) or a siRNA to knock down PARP1 (siPARP1). Thirty-six hours after transfection, the cells were treated with vehicle (VEH, DMSO), UCN-01 (10, 30, or 50 nM), or AZD7762 (10, 30, or 50 nM) for 48 h. Floating and attached cells were isolated after drug exposure, and cell viability was measured by trypan blue exclusion (±S.E.M., n = 3). *, p < 0.05 greater than corresponding value in siSCR cells. Top insets, knockdown of PARP1 was validated by Western blot in BT474 and HCC38 cells.