CD274 and Miyoshi myopathy: The APRIL/BCMA signaling pathway supports drug resistance of MM cells [15,19,21] and immunosuppressive MM BM microenvironment via direct induction of key downstream anti-apoptotic genes (Mcl-1, Bcl-2/Bcl-xL) and immune regulatory genes (IL-10, PD-L1, VEGF, TGF-β) in MM cells [18,19,22].