Schematic model of downstream signaling after GPCR activation. After chemokine binding, Gα and Gβγ subunits dissociate and GDP is exchanged for GTP. Gβ subunits, Rac1, Plcβ2, and Plcβ3 form a macromolecular complex upon activation, leading to generation of IP₃ (black circles), which in turn binds to IP₃-gated calcium stores leading to calcium release (black stars). Finally, activated LFA-1 upshifts to the high-affinity conformation. Dotted arrows, question marks, and molecules in light gray circles indicate potential alternative signaling pathways which might also play a role in downstream signaling leading to LFA-1 activation.