Figure 1 (A) Morphology of B16–F10 cells after 24-h incubation (scale bar=100 μm). Calcitriol is given as follows: ethanol 2% as negative control (Aa), cisplatin as positive control (Ab), calcitriol 125 ppm (0.325 μM) (Ac), 62.5 ppm (0.1625 μM) (Ad), 31.25 ppm (0.08 μM) (Ae), 15.63 (0.04 μM) (Af), 7.81 ppm (Ag). The arrows show the apoptosis cell death morphology. (B) Calcitriol increased the apoptosis process. White arrow points to the green dot accumulation reflecting the apoptosis in the cell. (C) Dose-dependent calcitriol treatment by various ranges of concentrations for 24 h showed inhibition of B16–F10 cells proliferation and decrease in viability at 125 ppm (0.325 μM) and 62.5 ppm (0.1625 μM). (D) IC50 was analyzed by using 4 parametric non-linear regression and plotted in GraphPad Prism. Each data point represents the average of 8 set duplications with SEM. Significance was considered * P<0.05, ** P<0.01, *** P<0.001.