DUX4 and facioscapulohumeral muscular dystrophy: Doxycycline induction of DUX4 expression in the MB135-iDUX4 cell line has been validated as an accurate cell model of the transcriptional consequences of DUX4 expression in FSHD muscle cells (Jagannathan et al., 2016) and in the early embryo (Hendrickson et al., 2017; Whiddon et al., 2017).