Figure 2. Concentration-dependent effects of imatinib on caspase-3/PARP cleavage and Akt phosphorylation. Subconfluent RGC-5 cells were maintained in serum free medium (-FBS) for 24 h or 48 h, during which time the cells were exposed to increasing concentrations of imatinib (10 µM to 30 µM). The cell lysates were subjected to immunoblot analysis using primary antibodies specific for A) caspase-3 that detects full-length and cleaved caspase-3, and B) PARP that detects full-length PARP and cleaved PARP, and C) phospho-Akt(Ser473) and total Akt. To normalize the expression of cleaved caspase-3 and cleaved PARP and the phosphorylation of Akt, we used the housekeeping gene β-actin as an internal control. The respective bar graphs shown are the mean±SEM values from 3 to 5 experiments. The asterisk and the sharp (hash mark) indicate a p<0.05 compared with the respective controls.