MYOD1 and myotonic dystrophy type 1: We next examined the effect of knockdown of COX-1 and COX-2 on MBNL1 expression in DM1 patient-derived induced pluripotent stem cells (MyoD-DM1-iPSCs), which were differentiated into myotubes by the induction of MyoD expression (Fig. 3a,b)32,33.