Effect of overexpression of E2F-1 on apoptosis following cytokine growth factor withdrawal.

Apoptosis following cytokine growth factor withdrawal is prevented by overexpression of E2F-1. Cells were cultured with or without IL-3 for 24 hours. (A) Cell cycle analysis was assessed by flow cytometry after staining with propidium iodide. Histograms show DNA content (x-axis) and cell number (y-axis). (B) DNA laddering apoptosis assay. Low molecular weight DNA was isolated and resolved on a 1.5% TreviGel 500 gel. Lane 1 shows 50 base-pair ladder; lane 2, control cells without IL-3; lane 3, control cells with IL-3; lane 4, E2F-1–overexpressing cells without IL-3; and lane 5, E2F-1–overexpressing cells with IL-3.