Cell cycle of the sorted cells in the twelve subfractions. Live cells were sorted according to the twelve subfractions, then fixed and stained with PI. A: Two examples of PI profile. Upper trace: (SSn, FSn) = (2.33, 1. 48), lower trace: (1.33, 1.24). The left peak corresponds to the G1 phase and the right region corresponds to S, G2 and M phase. B: Percentage of S, G2 and M phase cells. Shading corresponds to that in Fig. 4C.