MTT viability assay

MTT assay was performed as previously described (16,17). Briefly, PC3 and DU145 cells (1×10⁵ cells/well) were seeded into 48-well plates. After 8 h incubation, cells were transfected with pim-1 or control shRNA for 6 h, before being subsequently cultured for 48, 72 and 96 h. Next, 20 µl MTT agent (stock concentration 5 mg/ml) was added into each well followed by a further 4 h of incubation. Finally, 200 µl DMSO was added into the medium to dissolve the formazan crystals and incubated for 15 min at 37°C, and formazan was measured at a wavelength of OD490. The plates were read on a microplate reader (iMark™; Bio-Rad Laboratories, Inc.) before the data were analyzed. Survival rate (%)=100 × (OD 490 value of tested sample/OD 490 value of untreated cells).