TP53 and breast carcinoma: To address this issue, we examined the effect of shRNA-mediated p53 knockdown on the formation of nuclear actin filaments in human breast cancer MCF-7 cells bearing wild-type (WT) p53. The expression levels of p53 in DOXO-treated cells were evaluated by western blotting, which confirmed the efficient knockdown of p53 (Fig. S1).