Figure 4. Bcl-2 shRNA induced HLEC apoptosis. Apoptosis was measured by annexin V-FITC/PI staining and analyzed with flow cytometry. Horizontal and vertical axes represent labeling with annexin V-FITC and PI, respectively. The lower left indicates live cells; the lower right shows early apoptotic cells. The upper left shows necrotic cells, while the upper right demonstrates late apoptotic cells. The FACS plots shown were a representative of three independent experiments. The percentage of HLECs undergoing apoptosis was greatly increased in the PAMAM group (A) and liposome group (B), compared with the negative control group (C) and the empty control group (D).