Increased macrophage CEBPD promotes tumor resistance in two ways: (1) activating the pyrimidine metabolism pathway to produce the low molecular weight free metabolites in macrophages, as in the induction of gemcitabine resistance in pancreatic cancer cells (31); and (2) upregulating PTX3 expression, which enhances the resistance of breast cancer cells to cisplatin and 5-fluorouracil (50). The gene discussed is PTX3; the disease is breast cancer.