Rapamycin directly acts on survival and cell cycle of HMC-1 cell lines. (A) Comparative effect of rapamycin (5 nM) and imatinib (1 μM) on the induction of programmed cell death in HMC-1 and α-155 cells. Apoptotic and necrotic cells were followed by flow cytometry using an annexin V–FITC/PI kit. The percentage of dead cells located in top right histogram quadrant (annexin V⁺/IP⁺) is indicated. A representative experiment is showed out of 3. (B) Rapamycin effect on cell cycle in HMC-1 and α-155 cells. Cells were incubated in the presence of rapamycin (5 nM) or imatinib (1 μM) for 48 hours. Cell cycle was followed by flow cytometry using a Triton-PI buffer. Percentage indicates the number of cells at each cell cycle stage (G₀-G₁, S, and G₂-M). Data represent means ± SD of 3 separate experiments.