MBNL1 and myotonic dystrophy type 1: Furthermore, treatment of DM1 hiNeurons with ACT significantly reduced the number of nuclear RNA foci by more than 50% and treatment with erythromycin rescued mis-splicing of MBNL1 exon 5 and MBNL2 exons 5 and 8 up to 17.5%, 10% and 8.5%, respectively.