The production of IL-6, a major stromal cell-derived growth and anti-apoptotic factor for MM cells, was found to be markedly decreased in terminally differentiated OBs (91.2±5.7 and 15.1±2.7 pg/mL for 2 days in culture supernatants of untreated and terminally differentiated MC3T3-E1 cells, respectively). The gene discussed is IL6; the disease is Miyoshi myopathy.