Benzylidene-thiazolidine-2,4-diones inhibit Pim kinase activity in prostate cancer cells. A, Western blot showing the level of Pim-1 in endogenous (vector) and Pim overexpressor cell lines. B, dose-dependent reduction of Bad phosphorylation by 4a and 16a. Prostate cancer cells, DU145 or 22Rv1, were starved in serum-free medium overnight and then treated with the indicated amount of 4a or 16a or DMSO for 1 h. The level of phospho-Bad (Ser112) and total Bad were determined by SDS-PAGE followed by Western blotting. The level of endogenous phospho-Bad protein is significantly lower in vector-transfected cells compared with Pim-1-expressing cells (compare lanes 1 and 2). C, time course-dependent reduction of phospho-Bad (Ser112) in 4a- or DMSO-treated FDCP1-Pim cells. FDCP1-Pim cells were washed in PBS and placed in IL-3- and serum-free medium and 4a (5 μmol/L) or DMSO was added as a control. Lysates were prepared at the indicated time points and subjected to SDS-PAGE followed by Western blotting to measure phospho-Bad (Ser112) and total Bad.