During the past years, several clinical studies described ghrelin-producing NETs (Papotti et al., 2001; Volante et al., 2002; Taal and Visser, 2004) including six insulinomas, gastrinomas, vasoactive intestinal polypeptide (VIP)omas, non-functioning tumors (Volante et al., 2002) and as part of the multiple endocrine neoplasia type 1 (MEN-1; Iwakura et al., 2002; Raffel et al., 2005; Ekeblad et al., 2007). Here, VIP is linked to gastrin-producing neuroendocrine tumor.