Effect of REDD1 on efficacy of MLN4924. (A) REDD1 expression by western blot with MLN4924 or control over time in MM.1R and patient samples. (B) Silencing of REDD1 by siRNA blocks the signaling effects of MLN4924. (C) Silencing of REDD1 inhibits cytotoxicity effects of MLN4924 when compared with siRNA control, *P < .01; paired Student t test.