Dose-dependent effect of SAHA on cell cycle progression in human breast cancer cells. MCF7, MDA-MB-231, and MDA-MB-435 cells were treated with suberoylanilide hydroxamic acid (SAHA) at concentrations ranging from 0.1 to 10 µM for 24 hr or 48 hr, and then analyzed for cell cycle distribution by flow cytometry. The percentages of cells in sub-G1 (Apo.), G1, S, and G2/M phase are depicted as a function of dose. The percentages of cells distributed in G1 (■), S (▲), and G2/M (□) phases, as well as the percentages of apoptotic cells (Δ) are shown.