As CELF1 is increased in DM1 cardiac and skeletal muscles of both patients and mice (Savkur et al., 2001; Wang et al., 2007; Orengo et al., 2008), we assessed Bru-3 expression in larval muscles of pathological Drosophila lines. The gene discussed is CELF1; the disease is myotonic dystrophy type 1.