Interleukin-6 (IL-6) or insulin growth factor-1 (IGF-1) does not block CDDO-Im–induced cytotoxicity in MM cells. (A) MM.1S cells were treated with CDDO-Im (200 nM) or Dex (0.5 μM) in the presence or absence of IL-6 (10 ng/mL). At 24 hours cells were harvested and viability analyzed by MTT assays. Results are mean ± SD of 3 independent experiments (P < .005). (B) MM.1S cells were treated with CDDO-Im (200 nM) or Dex (0.5 μM) in the presence or absence of IGF-1 (50 ng/mL). At 24 hours cells were harvested and viability analyzed by MTT assays. Results are mean ± SD of 3 independent experiments (P < .005). (C-D) MM.1S cells were treated with CDDO-Im (200 nM) in the presence or absence of IL-6 (C) or IGF-1 (D). At 24 hours cells were harvested, and total protein lysates were subjected to SDS-PAGE analysis. Immunoblot analysis of the lysates was performed with anti-PARP Abs. FL indicates full length, and CF denotes cleaved fragment.