Effects of PF-228 on LN-mediated Gem chemoresistance in AsPC-1 cells. After pretreated with or without PF-228 (1 μM) for 30 min in serum-free medium, AsPC-1 cells were plated onto plastic or LN-coated 6-well plates and treated with Gem (0.1 μM) for 72 h in the continued presence or absence of PF-228. Cell apoptosis was examined by Hoechst staining (the arrow indicates the apoptotic cells) (A), flow cytometry analysis of Annexin-V labeling(B) and western blot analysis of cleaved caspase-3 protein expression(C). Bars represent the mean of three independent experiments ± SE. *, P < 0.05, vs. AsPC-1 cells without Gem treatment; #, P < 0.05, vs. Gem-treated AsPC-1 cells without PF-228 pretreatment on LN.