DUX4 and facioscapulohumeral muscular dystrophy: Crossing FLExDUX4 mice with ACTA1-MCM mice [54], a skeletal muscle-specific, TMX-inducible cre-expressing strain, produces double transgenic offspring that themselves represent a mild model of FSHD, and can be induced to develop a severe DUX4-dependent FSHD-like myopathy with low levels of TMX injected IP into adult animals.