Proliferation assay

Proliferation was determined with the MTT Cell Growth Determination Kit (Sigma-Aldrich, USA). MDA-MB-231 cells were transfected as described previously in a 6-well plate. Cells were trypsinized and plated in four 96-well plates at a cell density of 5 × 10³. Cells were allowed to grow for up to 48 h. Time 0 represents cells plated and analyzed on the same day (~6 h after cells attach). Cells were treated with 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) as instructed by the manufacturer. Briefly, 10 μL of MTT was added aseptically per well and incubated for 3 h. Medium was removed and 100 μL of MTT solvent added. Absorbance was read at 570 nm. Data represent mean ± SD, n = 3 samples/genotype from 3 independent experiments.