In conclusion, our study supports the existence of distinct MM cell types based on MITF expression levels based upon various characteristics without genetic alterations, that is, MITF’s role in (1) cell viability; (2) regulating cellular metabolic functions, particularly glycolytic activity potentially mediated by HIF-1α; and (3) 3D spheroid-forming efficacies. This evidence concerns the gene MITF and Miyoshi myopathy.