Knockdown of cytoplasmic p21 in cisplatin-resistant cells enhances apoptosis rate to cisplatin. (A) Representative western blot demonstrating the changes in cytoplasmic p21 protein levels observed in C13*/control, C13*/p21si and C13*/p21sm cells. (B) Apoptosis rates in response to cisplatin. (C) Corresponding western blot images of each group of cells depicted in A showing changes in cleaved caspase 3. (*, p < 0.05).