Diosgenin activates checkpoint proteins. (A) Incubation of MCF-7 (left panel) and Hs578T (right panel) cells with diosgenin increases expression of checkpoint kinase 1 (Chk1) and phosphorylated (activated) forms of Chk1 (p-Chk1Ser345), p-p53Ser15, p21, and p-Cdc25CSer216. Densitometric analyses for (B) MCF-7 and (C) Hs578T cells were performed using Digital Protein DNA Imagineware. β-actin was used to normalize the amount of protein in each lane. Data are shown as means ± SD for three independent experiments. * p < 0.05, ** p < 0.01, and *** p < 0.001 vs. control (Ctrl, 0 µM) group.