TGFB1 and colitis: Although Smad7 Tg mice do not spontaneously develop colitis, flow cytometry analysis of LPMC preparations showed that over-expression of Smad7 increases accumulation of CD3+ and CD4+ T cells in the intestinal lamina propria, perhaps reflecting the Smad7-mediated loss of the inhibitory effect of TGF-β1 on T cell proliferation and activation (17, 18).