Western blot and RT-qPCR analysis of the apoptosis-associated molecules in A-375 cells. (A) After cells were treated with different concentrations of penicitrinine A for 24 h, western blot analysis was performed using antibodies against Bcl-2, Bax and β-actin; (B) Densitometric analysis of Bcl-2 and Bax at protein levels; (C) A-375 cells were treated with 0, 12.5, 25 and 50 µM penicitrinine A for 24 h. The mRNA levels from whole cell lysates were analyzed by RT-qPCR, GAPDH was used as a loading control; (D) Summary of the ratio of Bcl-2 to Bax as demonstrated by histograms. Data are expressed as mean ± SEM (n = 3). * p < 0.05, ** p < 0.01 vs. the control group.