Recently, it was reported that SGK1 inhibition enhanced the cytotoxicity of bortezomib via activation of the JNK pathway and induction of CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP) expression, an essential factor of ER stress, in bortezomib-resistant MM cells [20]. Here, MAPK8 is linked to Miyoshi myopathy.