STAT3 and Miyoshi myopathy: To probe the significance of this signaling pathway in the survival and proliferation of MM cells, we treated human MM cell lines with a specific inhibitor of Stat3, S3I-201, which blocks Stat3 DNA-binding and transcriptional activities by inhibiting the phosphorylation of the tyrosine residue 705 on Stat3 (pStat3-Y705) [34], an event leading to Stat3 activation.