JS-K overcomes the protective effects of IL-6 and IGF-1, and adherence to patient BMSCs. MM.1S cells were treated for 48 hours with JS-K (0–2.4 μM) in the absence (□) or presence (■) of IL-6 (10 ng/mL) (A) or IGF-1 (50 ng/mL) (B), and without (□) or with BMSCs derived from MM patients 1(■) and 2 (□) (C). DNA synthesis was determined by measuring [3H]-thymidine incorporation during the last 8 hours of 48-hour cultures. Data represent means (± SD) of triplicate experiments.