These cell lines were useful to demonstrate that the burst-like feature of DUX4 expression is an intrinsic feature of the D4Z4 locus and, for the first time, showed that immortalized FSHD muscle cells can participate in muscle regeneration in vivo in immunodeficient host mice to overcome some of the limitations caused by the hominoid-specific features of DUX4. Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.