(A) Western blot analyses of HEXIM1 expression in MCF7 and MCF7/TOTR cells. MCF7/TOTR clone 1 cells were also treated with vehicle (DMSO), 5 mM HMBA, or 50 uM 4a1. (B) MCF7 or MCF7/TOTR (clone 1) or (C) MDA-MB-231, MDA-MB-468, MCF10A, and HBL-100 cells were treated as indicated for 7 days. MTT assays were then performed to assess proliferation. The right panel shows western blot analyses of HEXIM1 expression in MCF10A and HBL-100 cells. The figures are representative of 3 experiments. * p < 0.01 relative to DMSO treated cells.