We have demonstrated that PPM1D knockdown sensitizes resistant ovarian carcinoma cells to CDDP primarily by enhancing p53 activation via Ser15 phosphorylation (Fig. 1B and Fig. 2).9,11,33 However, the role of PPM1D in regulating p53 function goes beyond direct regulation, whereby PPM1D indirectly regulates p53 activation and stability. Here, PPM1D is linked to ovarian carcinoma.