Role of G protein–receptor coupling and PI3K for CCL3-elicited leukocyte responses. (A,C) Leukocyte firm adherence, and (B,D) transmigration were quantified in postcapillary venules of the cremaster muscle using RLOT in vivo microscopy as detailed in “Quantification of leukocyte kinetics and microhemodynamic parameters.” Panels show results for PBS-treated WT control mice as well as for WT mice receiving PTx, the PI3K inhibitors PI103 (pan-PI3K), AS605240 (PI3Kγ), and IC87114 (PI3Kδ), or respective drug vehicle after stimulation with CCL3 (mean ± SEM for n = 4 per group; #P < .05, vs unstimulated; *P < .05, vs vehicle). (E) Intravascular adherence and transmigration of fluorescence-labeled bone marrow leukocytes were quantified in the cremaster muscle using in vivo fluorescence microscopy as detailed in “Quantification of florescent leukocyte responses.” Panels show results for WT mice treated with PTx, the irreversible PI3K inhibitor wortmannin, or drug vehicle receiving leukocytes from WT donors pretreated with PTx, wortmannin, or drug vehicle after stimulation with CCL3 (mean ± SEM for n = 4 per group; #P < .05, vs unstimulated; *P < .05, vs WT→WT + drug vehicle).