Why would I see consitant decreases in cellular viability using MTT assay with the introduction lower concentrations but not with FACS?

I've been working with the MDA-MB 231, MDA-MB 157 and MCF7 breast cancer cells. With each cell line except for the 157s I saw a consistent trend in the decrease in % viability with the MTT assay....

15 January 2016 5,323 4 View