E2F-1 and cell cycle–dependent expression of cyclins A, B1, D1, and E after removal of cytokine growth factor.

E2F-1 restores cell cycle–dependent expression of cyclins A, B1, D1, and E following removal of cytokine growth factor. Cells were cultured in the presence or absence of IL-3 for 24 hours and then fixed in 90% methanol prior to staining with the appropriate cyclin antibodies and propidium iodide. Bivariate analysis was performed by flow cytometry; results are represented as contour plots, with DNA content corresponding to the x-axis and intracellular cyclin content corresponding to the y-axis. The corresponding DNA histogram for each study is shown as an inset, and the boxed region indicates the outer limits of the signal obtained with the use of a control primary antibody.