FAS and breast cancer: As shown Figure 4A, FAS RNAi at 40 nM severely suppressed constitutive FAS over-expression in MCF-7 and MDA-MB-231 when compared to control cells transfection with non-specific RNAi and FAS RNAi at 20 nM.To assess potential effects of α-mangostin on FAS knockdown breast cancer cells, FAS RNAi-transfected and negative control breast cancer cells were harvested, re-cultured in 96-well plates and cell viability was judged using a CCK-8 assay after exposure to various concentrations of α-mangostin.