The growth medium for propagating myoblasts contained 10 ng/ml of basic fibroblast growth factor (bFGF) plus 1 μM dexamethasone, as recommended in studies of normal and FSHD myoblasts [37,38] and as used in recent studies of DUX4 expression [7,8]. Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.