Thus, breast tumors generated by MMTV-neu:FAAH−/− mice expressed higher mRNA (Supplementary Fig. 9a) and protein (Fig. 6b) levels of Cxcr4 and Cxcl12 than their FAAH-expressing counterparts, which is consistent with their enhanced aggressive behavior and metastatic rate. The gene discussed is FAAH; the disease is breast neoplasm.