MBNL1 and myotonic dystrophy type 1: Finally, smFISH [r­(CUG)exp] and an immunofluorescenceassay (IFA; MBNL1) were used to evaluate whether the small moleculesinhibit the r­(CUG)exp–MBNL1 complex in DM1 patient-derivedmyotubes, as evidenced by reduction of nuclear foci.