Gα_i-signaling is independent of the presence of P-Rex1. (A) Adherent cells per square millimeter in cremaster venules before (left) and after (right) injection of 500 ng CXCL1 in WT (n = 4) and P-Rex1^−/− (n = 5) mice ± SEM. (B-C) Representative images of venules before (upper panel) and after (lower panel) CXCL1 treatment in WT (B) and P-Rex1^−/− (C) mice. (D) Numbers of adherent cells per square millimeter in untreated venules of the cremaster muscle of WT (n = 4) and P-Rex1^−/− (n = 5) mice before and up to 15 minutes after CXCL1 injection. (E) ICAM-1 adhesion to CD45⁺, Ly-6B.2⁺ and Gr-1⁺ WT (n = 3) and P-Rex1^−/− (n = 3) bone marrow cells without stimulation and after stimulation with CXCL1. Shown is mean fluorescence intensity of labeled ICAM-1 as determined by flow cytometry ± SEM. (F) HL-60 cells lines analyzed in a flow chamber adhesion assay coated with IL-8 and either an antibody specific for the open conformation of LFA-1 or isotype control. Depicted are mean adherent cells per field of view ± SEM. FOV, field of view; KC, keratinocyte-derived chemokine; Sc, scrambled. ^#P < .05.