DUX4 and facioscapulohumeral muscular dystrophy: To assess apoptosis in the three FSHD-like severity models, TUNEL assays were performed on TA muscles across the prior DUX4-FL induction time-courses in both the moderate and severe models as well as age-matched mild (No TMX) mice (Figs. 12 and 13, respectively and Figure S14).