Enhanced tumor growth and metastasis in IL-17–deficient mice. MC38 cells were inoculated into IL-17–deficient mice and normal wild-type mice as we described. (A) Enhanced tumor growth in IL-17–deficient mice. After tumor inoculation, tumor volume was measured as described in “Methods.” Results are expressed as mean ± SEM; n = 5 per group. (B) Enhanced tumor lung metastasis in IL-17–deficient mice. Thirty days after tumor inoculation, tumor colonies in the lungs were photographed and quantified; n = 6 per group.