Inhibition of Stat3 pathway induces apoptosis through caspase 3, 8 and 9 pathways in bladder cancer cells but not in bladder smooth muscle cells. (A) Cleaved caspase 3, 8 and 9 staining in dnStat3-transduced UMUC-3 and WH at 48 h post-infection and 31 h post-infection, respectively. Cells were transduced, fixed and then immunostained with anti-cleaved caspases 3, 8 and 9 antibodies. Cleaved caspases 3, 8 and 9 immunoreactivies were observed in cells transduced with rAd/dnStat3 but not in the cells transduced with rAd/eGFP or negative control. Cleaved caspase 3, 8, 9: anti-cleaved-caspases 3, 8, & 9 antibody immuno-fluorescent staining; Unt: untreated; DAPI: nuclear staining with DAPI; phase:phase-contrast. Magnification of images was 100×. (B) 45–75% of UMUC-3 and WH cells transduced with rAd/dnStat3 were cleaved caspase 3, 8, and 9 positive. (C) STA-21 also induced apoptosis (cleaved caspase 3 staining) in 253J, WH and UMUC-3 cells but not in BdSMC cells.