However, the relative immaturity of the hiPSC-CMs may account for the absence of CELF1 overexpression in the DM1 cell lines compared to the CTRL cell lines, as CELF protein expression is known to be elevated during embryogenesis and fetal heart development (Kalsotra et al., 2008). This evidence concerns the gene CEBPD and myotonic dystrophy type 1.