TM4SF1 and prostate carcinoma: While TM4SF1 is a transmembrane protein 3, also found in the cytoplasm 29, and tentatively in nuclei of both cultured endothelial cells and tumor cells 9, and abundantly expressed on the plasma membrane and intracellular vesicles of lung, breast, colon, ovarian, renal, and prostate carcinomas and low expressed in normal vascular endothelium 7, 8, the cellular localization of TM4SF1 in gastric tissue remains obscure.