Fig. 3.

Musclin production is stimulated by Ca²⁺-dependent Akt phosphorylation. (A) Representative Western blots of Akt, FOXO1, and GAPDH from cultured murine primary myoblasts in 1 mM Ca²⁺ without ionophore (control) vs. with 1 µM ionophore A23187 (Sigma-Aldrich). (B and C) Summary statistics for phosphorylated Akt (pAkt) and phosphorylated FOXO1 (pFOXO1) normalized to GAPDH (B) and total Akt and total FOXO1 (C), respectively, with (gray) and without (white; control) 1 µM ionophore. *P < 0.05 vs. control. (D and E) Summary statistics for musclin mRNA normalized to HPRT in murine cultured primary myoblasts exposed to various concentrations of ionophore, Ca²⁺ and Akt inhibitor-viii (D) and human cultured primary myoblasts exposed to no Ca²⁺ vs. 1.0 mM Ca²⁺ and various doses of ionophore, by densitometry of Western blots (E). *P < 0.05 vs. no ionophore (D) or vs. Ca²⁺-free (E).