Fig. 2. Effect of 15d-PGJ2 on cell cycle reentry of MCF-7 cells. MCF-7 cells were incubated for 40 h in DMEM with 0.5% serum to synchronize cells in G0/G1. At T=0, the medium was changed to fresh medium containing 10% serum with vehicle or 15d-PGJ2 (final concentration, 20 µM). Control and treated cells were processed at various times and subjected to FACS analysis to determine cell cycle phase. A, FACS analysis of cells restimulated with 10% serum plus vehicle (upper) or 10% serum plus 15d-PGJ2 (lower). B, fraction of cells in S-phase at various time points. , cells stimulated with 10% serum plus vehicle. , cells stimulated with 10% serum plus 15d-PGJ2.