However, PACAP and its various receptor forms have been found expressed in human NE tumours such as pheochromocytomas and neuroblastomas (Reubi et al, 2000; Sherwood et al, 2000), and PACAP has been found to modulate rat gastric ECL cell proliferation (Läuffer et al, 1999), indicating a possible role of PACAP in NE GI tumour cell biology as well. Here, ADCYAP1 is linked to pheochromocytoma.