Inhibition of p53 by specific siRNA to p53 in A2780 cells. siRNA against p53 (SMARTpool p53) were transfected into A2780 cells using Lipofectamine 2000. A negative nonspecific siRNA was used as control. Twenty-four hours after transfection, cells were treated with cisplatin for 1 hr at 3 μM concentration. At the end of 1 hr exposure to cisplatin, cells were washed and incubated with fresh media. The protein level of p-p53(Ser15), p-p53(Ser20), p53, p-Chk2(Thr68), Chk2, p21, and β-Actin were determined by Western blotting.