We observed a diffuse distribution of MBNL1 and MBNL2 throughout the nuclei of control cells, whereas DM1 cells displayed a dotted pattern that colocalized with RNA foci, supporting the hypothesis that these splicing regulators are sequestered in DM1 NPCs (Fig. 2A, B). This evidence concerns the gene MBNL1 and myotonic dystrophy type 1.