Rap1-deficient T cells develop normally but are defective in adhesion to ICAM-1 and homing to peripheral lymph nodes. (A) Immunoblot for Rap1 (antibody detects both Rap1a and Rap1b) of lysates of T cells, thymocytes, and splenocytes from mice of the indicated genotypes. β-tubulin serves as a loading control. (B) Percentages of thymocytes of animals with the indicated genotypes that were characterized by flow cytometry as CD4⁺, CD8⁺, double-positive, or double-negative. (C) Percentage of resting or stimulated (anti-CD3 or phorbol myristate acetate) splenic T cells from animals with the indicated genotypes adherent to ICAM-1 coated wells after washing. (D) Absolute number of CD3⁺ cells in thymus, 1 mL blood, spleen, and pLNs of animals with the indicated genotypes. (B, C, and D) Results plotted are mean ± SD; n = 4; **P < .01, ***P < .001.