Cellular accumulation of TGF-α and compensatory proliferation induced by recombinant TGF-α. (A) Colonic tissue sections from unchallenged and challenged WT and ADAM17^ex/ex mice (4 d, 2% DSS) were stained for TGF-α. Representative microscopic pictures of three mice per group are shown. Bars, 100 µm. (B) Colitis was induced in WT (n = 5) and ADAM17^ex/ex (n = 9) mice with 2% DSS for 10 d. ADAM17^ex/ex mice were injected daily with recombinant TGF-α (15 µg/mouse; n = 5) or with PBS (n = 4). Representative microscopic images of one experiment with five WT mice, four ADAM17^ex/ex mice treated with PBS, and five ADAM17^ex/ex mice treated with TGF-α are shown. Bars, 100 µm. The experiment was performed twice with similar results. (C) Colitis was induced in WT and ADAM17^ex/ex mice with 2% DSS and the animals were injected daily with the EGF-R ligand EGF (15 µg/mouse; WT, n = 3; ADAM17^ex/ex mice, n = 8) or with PBS, (WT, n = 8; ADAM17^ex/ex mice, n = 9) and body weight was recorded. Data were pooled from two independent experiments.