FIG. 1.

Rapamycin delays G₁-phase progression in U2OS cells. U2OS cells were serum deprived for 30 h and then refed with DMEM-10% FBS for the indicated time points between 12 and 24 h in the absence (−Rapa) or presence (+Rapa) of rapamycin at 20 ng/ml. DNA content was determined on a flow cytometer. DNA content histograms are shown in panel A with the percentage of cells in each cell cycle phase indicated. Propidium iodide positive staining is graphed on the x axis with cell number on the y axis. Quantitation of the percentage of cells that have entered S phase at the various time points is shown graphically in panel B.