Since IL-1β has been reported to induce COX-2 in various tissues including glia, it has been proposed that a vicious cycle occurs whereby ATP release (from cell death for example) leads to P2X7R activation, IL-1β release, COX-2 induction and further cell death with consequent ATP release; this type of self-perpetuating cycle may underlie lesion expansion particularly in stroke and TBI. This evidence concerns the gene IL1B and stroke disorder.