While it is widely accepted that CCR7 and its ligands CCL19 and CCL21 are the key chemokine receptor–ligand pairs that control DC migration under most circumstances (Alvarez et al, 2008), León et al (2012) suggested that during helminth infection, the essential chemokine that governs DC Th2 induction is CXCR5 (León et al, 2012). The gene discussed is CCL21; the disease is helminthiasis.