Figure 1: Effects of HL on cell cycle and apoptosis in A549 cells. (A) Cell cycle analysis as assessed by flow cytometry. A549 cells were treated with 100-500 μM HL for 48 hours. The cell cycle distribution was measured by PI staining and flow cytometry. (B) Induction of G0/G1 arrest by HL. A549 cells were treated with 200 μM HL for 6, 24 or 48 hours. (C) Induction of apoptosis by HL. A549 cells were treated with 100-500 μM HL for 48 hours. (D) Confocal microscopy images of active caspase-3 (green) in A549 cells after the treatment of HL (400 μM) for 24 hours. Data are the mean ± standard error (n=3) from three independent experiments; arrows indicate G0/G1 arrest; scale bars: 20 μm.