New research from the Jane-Wit laboratory showed that Sonic Hedgehog (SHH) signalling from damaged graft endothelium drives vasculopathy by promoting proinflammatory cytokine production and NLRP3-inflammasome activation in alloreactive CD4+PTCH1hiPD-1hiT memory cells, offering new diagnostic and therapeutic strategies. The gene discussed is CD4; the disease is vascular disorder.