Mice lacking CXCL13 and CXCR5 had impaired tumor formation after being exposed to environmental carcinogens such as polycyclic aromatic hydrocarbons (PAH), whereas lung tumors developed in mice after being exposed to the PAH benzo(a)pyrene (Ba[a]P) had elevated CXCL13 levels, highlighting the importance of the chemokine axis in lung tumorigenesis [127]. Here, CXCL13 is linked to neoplasm.