NAC (nascent polypeptide associated complex) is a heterodimer consisting of an alpha and a beta subunit. skNAC (skeletal and heart muscle-specific form of alphaNAC) is a variant of alphaNAC, which is induced in muscle differentiation and regeneration. We show here that skNAC expression is regulated by p38 MAPK, which plays a crucial role in myogenesis. Furthermore, inhibition of skNAC expression in myoblasts via specific siRNAs might lead to disturbed incorporation of myosin heavy chain (MyHC) into sarcomeres, however, it has no inhibitory effect on absolute MyHC protein levels. Taken together, our data suggest that skNAC regulates specific aspects of myogenesis.