Expression of HO-1 and HO-2 isoforms in mucosa and skin. (A) HO-1 is not exclusively expressed in the oral mucosal epithelium, but also present in the epidermis of skin from the back of a rat and in the intestines (original magnifications, × 100 and × 250, respectively). Furthermore, HO-1 expression is evident in human epidermis and infiltrated leukocytes of a patient suffering from chronic inflammation (arrows; original magnification, × 250). (B) HO-2 is expressed both in the epithelial as well as the dermal layer of mucosa and skin (mucosal, back of the rat, and intestines; arrows; original magnifications, × 100 and × 250, respectively). HO-2 is also expressed in a patient suffering from chronic inflammation.