Using the CXCR4 antagonist, AMD3100, and a neutralizing anti-CXCL12 antibody in a model of urinary tract infection, Isaacson et al. confirmed that the disruption of the CXCL12/CXCR4 interaction significantly decreased the accumulation of these immune cells at the site of infection. The gene discussed is CXCL12; the disease is infection.