Global gene expression profiling of GOT1 ileal carcinoid cells revealed a marked upregulation of CXCR4 in response to hypoxia, and the agonist stimulation of CXCR4 was able to activate the mitogen-activated protein kinase (MAPK) p42/44 pathway, resulting in increased tumor cell migration [13]. This evidence concerns the gene CXCR4 and carcinoid tumor.