Inhibitory effects of DMC on stimulation by IL-6 or IGF-1. MM1.S and MM1.R cells were cultured under low serum conditions (RPMI with 1% FBS) overnight. The medium was then replaced with RPMI (without FCS) containing increasing concentrations of DMC as indicated. After 1 hour, the cells were stimulated with either 25 ng/mL of IL-6 (A), or 200 ng/mL of IGF-1 (B). Fifteen minutes later, cells were lysed and analyzed by Western blot analysis as detailed in the legend to Figure 4.