In our present study, the inhibitory effects of curcumin on the development of GVHD were associated with attenuated expressions of c-Fos/c-Jun in the epithelial tissues of skin (including keratinocytes) and intestine, suggesting that decreased AP-1 signaling in skin keratinocytes and intestinal epithelial cells may at least contribute to the attenuated severity of acute GVHD in animal models. Here, JUN is linked to graft versus host disease.