In the same cellular model (T10 and T15 DM1 myotubes) we previously described a splicing unbalance of MBNL1 and Insulin Receptor and nuclear accumulation of CUG-containing DMPK mutant transcripts (foci) [24], strongly suggesting that the size of CTG repeats in the DMPK gene plays a role in determining the splicing unbalance of all analyzed genes. This evidence concerns the gene INSR and myotonic dystrophy type 1.