P-selectin induced by VAP-1 is functional in vivo. (A) Frozen section binding assays were used to analyze lymphocyte binding to HEVs in mesenteric lymph nodes obtained from VAP-1 KO mice and VAP-1 KO-TG mice, which were treated or not treated with methylamine in the drinking water. Lymphocytes were from nontreated wild-type animals. The results are shown as relative adhesion ratios (mean ± SEM), in which the number of HEV-bound lymphocytes in VAP-1 KO in the absence of methylamine treatment is 1.0 by definition. (B) The function of P-selectin was blocked by preincubating the sections with anti–P-selectin antibody (or control antibody) before the binding assays. The results are shown as percentage of control binding (number of HEV-bound lymphocytes in the presence of nonblocking control mAb) (mean ± SEM). n = number of mice in each group. *P < .05, **P < .01.