S100B in myoblasts regulates the transition from activation to quiescence and from quiescence to activation and reduces apoptosis

► Differentiating myoblasts downregulate S100B expression via p38 MAPK. ► Serum mitogens upregulate S100B expression in myoblasts. ► Myoblasts induced to quiescence downregulate S100B expression. ► Downregulation of S100B is required for efficient myoblast differentiation. ► Downregulation of S100B is required for myoblast to attain quiescence in vitro.