Besides a role in which HIF1α can contribute to DUX4 toxicity in proliferating FSHD myoblasts [28], we also found that DUX4 suppressed the role of HIF1α in promoting early differentiation, thus interfering with FSHD muscle regeneration (Fig. 6). This evidence concerns the gene DUX4 and facioscapulohumeral muscular dystrophy.