Gene expression analysis in pretumor mammary glands showed that all growth factors and chemokines observed to be elevated before tumor development in continuous HFD mice at 13 weeks of age (i.e., Tgfa, Ccl1, Ccl17, Ccl20, Ccl22, and Tgfb1) were elevated in LFD-HFD mammary glands at this time. The gene discussed is CCL20; the disease is neoplasm.