Transepithelial leukocyte migration during pneumococcal infection required the lipid chemoattractant hepoxilin A3 (HxA3), an eicosanoid synthesized from arachidonic acid via 12-lipoxygenase (12-LOX) and secreted by lung epithelial cells (9). The gene discussed is ALOX12; the disease is pneumococcal infection.