CCK modifies the migratory abilities, proliferation, and survival of tumor astrocytes (De Hauwer et al., 1998; Lefranc et al., 2002) and lymphocytes (Medina et al., 1998), and guides migrating gonadotropin-releasing hormone-1 (GnRH-1) neuroendocrine neurons into the brain (Giacobini et al., 2004). Here, GNRH1 is linked to neoplasm.