IMiD1 blocks the antiapoptotic effect of IGF-1 in MM.

(A) DNA binding activity of the transcriptional factor NF-κB was quantified in MM.1S cells pretreated with or without 1 μM IMiD1 for 3 hours, and then treated for an additional 4 hours with or without 200 ng/mL IGF-1 or 50 ng/mL TNF-α. IMiD1 inhibited activation of NF-κB induced by IGF-1 and TNF-α in MM cells. (B) Immunoblotting analysis for the antiapoptotic molecules cIAP-2 and FLIP in MM.1S cells. Treatment with IGF-1 (200 ng/mL for 24 hours) increased the protein levels of the caspase-8 inhibitors cIAP-2 and FLIP; IMiD1 (1 μM) inhibited this effect.