The lack of pancreatic fibrosis in diseased Tgfbr2fspKO pancreata is likely to be due to the inability of fibroblasts in the transgenic mouse to respond to TGFβ, a potent mediator of collagen expression.26 The development of mAIP occurs in mice of both genders early in life, whereas human AIP typically affects older males.2 It also remains unclear why our Tgfbr2fspKO mice have involvement of some of the organs seen in IgG4-related sclerosing disease, including pancreas and salivary gland involvement, but not other organs such as lung or kidney. The gene discussed is TGFB1; the disease is autoimmune pancreatitis.