IRF4 and AL amyloidosis: In myeloma cells, IRF4 is known to up-regulate over 100 genes (as compared to primary plasma cells), and many amongst them are associated with cellular growth and survival, like MYC. Because of pleiotropic effects of IRF4 in myeloma cells, multiple myeloma is said to be “addicted” to IRF4, with lower expression thereof severely hurting myeloma cells (Shaffer et al. 2008).