Arrest of NPC cells at S phase of the cell cycle by treatment with ApoG2. Arrest of NPC cells at S phase by ApoG2. C666-1 (A), CNE-1 (B), CNE-2 (C) and HONE-1 (D) cells were treated with 5 and 10 μ M ApoG2 for 48 h. DNA cell cycle analysis was performed using PI staining and flow cytometry. Each histogram is representative of three experiments. (E) Cell cycle analysis showed that ApoG2 treatment induced a conspicuous increasing of cells in S phase in four NPC cell line at 48 h. Bar heights, average of three independent experiments; bars, SD.