The analyses of primary tumor cells from patients with MM and established MM cells have consistently revealed that STAT3 is constitutively active in approximately 40–60% of MM tumors (Catlett-Falcone et al., 1999; Quintanilla-Martinez et al., 2003; Bharti et al., 2004; Kannaiyan et al., 2012; Sikka et al., 2014). This evidence concerns the gene STAT3 and Miyoshi myopathy.