Fig. 5. Characterization of EXP proteins in mouse tissues and during myoblast differentiation. (A) Immunoblot analysis using anti-hEXP42 antibodies showing that the EXP proteins are expressed in muscle and eye. Equal protein loads (15 µg/lane) were confirmed by Coomassie Blue staining (data not shown). (B) EXP expression is induced during myoblast differentiation. Immunoblot showing myosin heavy chain (αmyosin HC), mEXP42 (αhEXP42) and CUG-BP1 (αCUG-BP1) protein levels prior to (Day 0) and during (Days 1–5) myoblast differentiation. (C) Phase and immunofluorescence microscopy showing two examples of multinucleated myotubes, present on Day 4 following induction of myoblast differentiation, as well as undifferentiated myoblasts.