Pannexin-1 hemichannels facilitate ATP release at the immune synapse. Stimulation of the TCR leads to redistribution of pannexin-1 to the immune synapse (A). Treatment with the gap channel inhibitor carbenoxolone reduces ATP release and IL-2 gene transcription upon CD3/CD28 stimulation. (B). The pannexin-1 specific inhibitor ¹⁰panx-1 reduced Ca²⁺ entry compared with the control peptide (^scpanx-1), or to CD3 stimulation without any peptide (control) in human PBMCs (C) and IL-2 transcription in human PBMCs and mouse splenocytes (D). *P ≤ .05, **P ≤ .01 compared with CD3/CD28-stimulated controls.