Effects of an antiulcer drug, geranylgeranylaceton (GGA), and/or heat-stress on 72 kDa beat shock protein (HSP72) expression and protein content in cultured skeletal muscle cells were studied. Mouse skeletal muscle cells (C2C12) were subjected to either 1) control (cultured at 37 degrees C without GGA), 2) GGA administration (10(-11)-10(-8) M), 3) heat-stress at 41 degrees C for 60 min, or 4) GGA administration combined with heat-stress. Expression of HSP72 was up-regulated by GGA administration. Heat-stress further enhanced the GGA-related up-regulation of HSP72. Administration of GGA caused an increase of muscular protein content as a dose-dependent manner. Protein synthesis was also stimulated by heat-stress alone in myotubes. It was suggested that GGA stimulates the differentiation of myoblasts and protein synthesis. These observations may also suggest that the administration of GGA could be one of the useful tools to gain muscular mass not only in athletes, but also in patients during rehabilitation. (c) 2007 Elsevier Inc. All rights reserved.