In DM1 neurons and muscles, DMPK 3’UTR CUGexp RNAs provide a large array of high-affinity binding sites for muscleblind-like (MBNL) RNA-binding proteins resulting in MBNL inhibition and formation of biomolecular condensates known as RNA foci16–22. This evidence concerns the gene DMPK and myotonic dystrophy type 1.