Il17a mRNA expression returned to control mouse levels in KC-Tie2–Il17re-, KC-Tie2–Il17c-, and KC-Tie2–Il17ra-deficient mice, and IL-17A protein also returned to control mouse levels in KC-Tie2–Il17re- and KC-Tie2–Il17c-deficient mice but remained increased in KC-Tie2–Il17ra-deficient animals (Figure 5, D and E), despite the lack of skin inflammation. This evidence concerns the gene IL17A and dermatitis.