“…However, in vertebrates, other than connexins, there is no other protein family that has acquired the evolutionary advantage of direct and regulated intercellular exchange of signaling molecules barring the exception that pannexin 1 potentially acquires this capacity in rare situations ( 26 , 27 ). Nevertheless, overwhelming experimental evidence now points to cell surface connexin hemichannels having key roles in normal chordate physiology, pathology, and tissue injury, all of which are reviewed in detail elsewhere ( 28 , 29 , 30 , 31 ).…”