FTY720 inhibited proliferation and induced apoptosis in MM-BMSCs. Normal-BMSCs (n = 2) and MM-BMSCs (n = 21) were cultured with or without FTY720 (1 µM). (A) Cell viability after 48 hours. Values represent proliferation rate normalized by control (FTY720⁺/FTY720^–) ± standard deviation. (B) Caspase-3/7 activity measured after 48 hours. Data represent fold increase compared with control (without FTY720) ± standard deviation. (C) Rates of apoptosis in normal-BMSCs and MM-BMSCs treated with 1 µM of FTY720 for 48 hours, determined by Annexin V and propidium iodide (PI) staining and flow cytometry. *P < .01 vs control (without FTY720).