Semaphorin 4D, which takes advantage of platelet-derived growth factor B to modify pericyte coverage, induces and recruits macrophages in invasive tumor fronts to secrete stromal cell-derived factor 1, thus communicating with tumor cells in which CXCR4 promotes tumor invasion and metastasis in pancreatic NETs [88]. The gene discussed is CXCR4; the disease is neoplasm.