Given that gastrin is expressed early in the development of human pancreatic ductal intraepithelial neoplasia (PanIN) [40], and that pancreatic tumor cells secrete biologically active forms of gastrin into the tumor microenvironment [41], PSCs may be responding to gastrin in a paracrine fashion that stimulates desmoplastic responses. This evidence concerns the gene GAST and pancreatic neoplasm.