MAPK8 and dermatomyositis: According to studies on DM pathogenesis, skeletal muscle inflammation induces muscle atrophy by inhibiting PI3K–Akt–mediated myogenic signals, which are activated by AMPK, p38 MAPK, JNK, mTOR, and IGF-1 (Stitt et al., 2004; Li et al., 2005; Kim et al., 2017; Kim et al., 2018).