FIG. 5.

A partial cell cycle that includes mitosis but lacks S phase is sufficient for transduction by FV vectors. (A) Human fibroblasts were synchronized at the G₁/S border and exposed to retroviral vectors at the beginning of S phase (S-cycle and S-G₂-M-G₁) or 9 h later (M-cycle and G₂-M-G₁). Aphidicolin was added 9 h after the initial withdrawal to prevent additional DNA synthesis in the S-G₂-M-G₁ and G₂-M-G₁ treatments. Solid lines delineate phases of the cell cycle traversed by the cells, and dotted lines delineate blockage of these phases during the transduction period. Aphidicolin treatment is depicted by a white bar. The durations of cell cycle phases during the experiment are indicated at the top. (B) The percent transduction relative to that obtained in the S-cycle treatment is shown for each treatment in panel A.