In the early stage of renal fibrosis (Day 3), in situ TG1 activity was markedly enhanced in the renal tubule, whereas TG2 activity increased only in the interstitial area; in later stages of renal fibrosis (Day 7 and 14), TG1 activity was strongly distributed in both the renal tubule and interstitial area, whereas TG2 activity localized to the extracellular space, including the area around the renal tubule and interstitial area. Here, TGM2 is linked to renal fibrosis.