A previous study showed that the Stat3 inhibitor C188-9, which blocks the phosphorylation of Stat3’s tyrosine 705 residue, efficiently ameliorates mast cell–mediated systemic anaphylaxis through a regulation of vascular permeability, based on a Stat3-transcriptional activity–dependent tight junction stabilization in endothelial cells [37]. The gene discussed is STAT3; the disease is anaphylaxis.