PGE2 and prostaglandin E2 receptor EP4 (EP4) subtype combine on multiple cell types: tumor cells, tumor-infiltrating immune cells, and lymphatic endothelial cells (LECs), EP4 activation on cancer cells, and macrophages upregulated vascular endothelial growth factor c/d (VEGF-C/D) production. This evidence concerns the gene PTGER4 and cancer.