These results strongly suggest that PKRA7 could inhibit pancreatic tumor growth via a different mechanism by blocking PKR1- and PKR2-expressing macrophages from infiltrating into the tumor microenvironment rather than suppressing angiogenesis, an observation consistent with the phenotypic features of human pancreatic cancer as poorly vascularized but exhibiting abundant desmoplastic fibrosis and containing large number of infiltrated myeloid cells including macrophages [10], [15]. This evidence concerns the gene PROKR2 and familial pancreatic carcinoma.