In this experiment, we studied the effects of breed differences on the protein expression of adipogenic transcription factors, the C/EBP family (C/EBP alpha, C/EBP beta-LAP, C/EBP beta-LIP and C/EBP delta) and PPAR gamma, in the adipose tissues of Japanese Black (Wagyu) and Holstein steers from various anatomical sites (subcutaneous, intermuscular, and mesenteric) at different fattening periods (19 and 24 months of age). The expression of C/EBP beta-LAP and C/EBP alpha in the mesenteric fat tissue of Wagyu at 19 months of age was significantly higher than that of Holstein. The expression of C/EBP6 in the subcutaneous, intermuscular and mesenteric fat tissue of Wagyu at 19 months of age was significantly higher than that of Holstein. The plasma insulin concentrations of Wagyu steers at 19 months of age tended to be higher than those of Holstein. No significant differences in the expression of the adipogenic transcription factors and plasma insulin concentration were observed between the breeds at 24 months of age. These results suggest the existence of breed difference on the expression of the C/EBP family between fattening Wagyu and Holstein steers at 19 months of age, whereas breed difference might have disappeared before 24 months of age. (c) 2008 Elsevier Ltd. All rights reserved.