Besides its classical functions as a neurotransmitter in the central nervous system, local
mediator in the gastrointestinal tract and vasoactive agent in the blood, serotonin has more
recently emerged as a growth factor for human tumor cells of different origins (carcinomas,
glioma and carcinoids). Several data are also available on serotonin involvement in cancer
cell migration, metastatic dissemination and tumor angiogenesis. The serotonin-induced
signaling pathways that promote tumor progression are complex and only partly understood …