Effect of CP1 on CH-1a-induced apoptosis during the late phase of infection. (A and B) Marc-145 cells were treated with or without CH-1a (MOI =0.01) in the presence of CP1 (480 μg/ml) or YPD (control) for 24, 48, or 72 h, and then stained with FITC–annexin V (green) and PI (red) for 15 min in the dark for the IFA analysis (A). The number of cells calculated from IFA stained with annexin V and PI per foci were counted at the indicated times (B). (C) The inhibitory effects of CP1 on apoptosis were confirmed with the transcript levels of caspase-3 in virus-infected cells treated with CP1 for 72 h. Data are the results of three independent experiments (means ± SE). Significant differences compared with the YPD-treated control group are denoted: *P <0.05, **P <0.01, or ***P <0.001.