MMP13 and pemphigus foliaceus: Further supporting this view, our in vitro and in vivo studies demonstrated that the gelatinolytic activity of TGFβ-treated hIPF-Lfs was enhanced by both CSP-dependent IRE1α suppression and 4μ8C-dependent IRE1α inhibition, and that the results of our immunohistochemistry analyses showed the reduction in collagen 1 and the elevation of MMP13 signals in the CSP-treated PF in two different mice models.