Tumor cell viability determination using the MTT assay

To assess the effects of ginsenoside Rg3 on tumor cells in vitro, B16 cells were plated in 96-well plates at a density of 4×10³ cells/well and incubated overnight, and were then treated for 72 h with a series of concentrations (1, 2.5, 5, 7.5, 10, 12.5 or 15 µg/ml) of Rg3 (Shanghai Haoran Biological Technology Co., Ltd., Shanghai, China). Rg3 was dissolved in dimethyl sulfoxide (DMSO; Sigma-Aldrich; Merck KGaA, Darmstadt, Germany) and filtered through a 0.2-µm membrane before use. At the end of the experiments, cell proliferation was assessed by 10% MTT (Sigma-Aldrich; Merck KGaA), as described previously (46).