MDM2 and skin neoplasm: As shown in Figure 2A, the estradiol resulted in approximately 60% inhibition efficiency on cell proliferation in the GLL19 and A375 cells, and the effects were more markedly (P<0.01) than that in Hacat cells which are immortalized but not malignant keratinocyte, indicating that the decrease of MDM2 were critical for the estradiol-induced proliferation inhibition in skin cancer cells.