Protein extracts from S. macrurus blastema (SmBE) modulates the expression of differentiation regulators and markers. Western blot analyses of C2C12 myoblasts cultured in differentiation medium (DM) with extract from adult muscle extract (AM) or 1-week blastema (SmBE) at 0.05 mg/ml or without extract (−) for 0, 1 and 2 days. Total protein (50 μg) was resolved by 4-15% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to a PVDF membrane and probed with antibodies against MHC, MyoD, myogenin, Myf5, p21, cyclin D1, and pRb antigens. Top arrow indicates hyperphosphorylated pRb and bottom arrow indicates hypophosphorylated pRb. Membranes were also probed with anti-β-actin antibody to demonstrate equal loading.