Fig. 4.

p38 siRNAs suppress DUX4 in FSHD myotubes. (A) 54-2 (FSHD1) myoblasts were transfected with siRNA targeting p38α (si-p38α), p38β (si-p38β), or control (si-CTRL) siRNAs, as indicated, 24 hours prior to induction of differentiation. Cells were induced to differentiate and harvested 40 hours later. RNA was isolated and analyzed for p38 (left panel) and DUX4, MBD3L2, ZSCAN4, and LEUTX (right panel) expression levels. (B) MB200 (FSHD2) myoblasts were transfected with the indicated siRNAs on two consecutive days prior to inducing differentiation. Twenty-four hours after the second transfection, cells were induced to differentiate and RNA was isolated 40 hours later and analyzed as in (A). Data are expressed as relative expression (mean with S.D.) with the expression in the presence of si-CTRL set to 1. *P < 0.01 vs. si-CTRL (one-way ANOVA with Dunnett’s post test).