The MCF-7 cell growth inhibition assay was carried out as described previously45 (link). A broth micro-dilution method was used to determine the growth inhibition IC50 values. Compounds were half-log serial diluted using cell culture media into 96-well TC-treated round bottom plates (Corning Inc., Corning, NY). Cells were plated at a density of 5000 cells/well and then incubated under the same culture conditions for 2 days at which time an MTT ((3-(4,5-dimethylthi-azole-2-yl)-2,5-diphenyltetrazolium bromide) cell proliferation assay (ATCC, Manassas, VA) was performed to obtain dose response curves.