JUNB and Miyoshi myopathy: Given the principal role of c‐FOS in the activator function of the IKZF1 complex in MM cells, the sole targeting of IKZF1/IKZF3 by lenalidomide might be insufficient for inducing the complete down‐regulation of IRF4 expression and subsequent cell death because residual AP‐1 activity could sustain the transcription of IRF4 (Figure 8, middle panel).