MAPK8 and Miyoshi myopathy: In order to clarify the involvement of JNK, we first investigated the role of JNK in the regulation of p53-mediated apoptosis induced by RITA in MM cells by using a JNK specific inhibitor, SP-600125 which exhibits significant selectivity for JNKs leading to inhibition of both phosphorylation of c-Jun and JNKs [29].