Taken together these data suggest that Arf1 is the predominant Arf-isoform in neuroendocrine BON cells and that its association with neuroendocrine vesicles may suggest a function for Arf1 in deregulated secretion of NETs (expression of Arf1 in samples of pancreatic human NET samples was substantiated by immunohistochemistry for Arf1 expression in samples of pancreatic insulinomas and gastrinomas; Fig. S6). This evidence concerns the gene ARF1 and gastrin-producing neuroendocrine tumor.