Model of SS RBC activation by epinephrine. We previously demonstrated that stimulation of ARs by epi affects downstream events via AC through activation of Gαs protein complex. Increased intracellular cAMP as a result of activation of AC leads to activation of PKA, which acts as a downstream effector to up-regulate SS RBC adhesion mediated by activation of LW, which becomes phosphorylated and preferentially recognizes the endothelial αvβ3 integrin. We now propose that epinephrine acts via stimulation of RBC β₂-ARs and leads to activation of LW to interact with both endothelial cells as well as leukocytes.