GPC1 and breast cancer: This isoform shows increased expression in gliomas, where it acts to enhance FGF signaling and mitogenesis (50); in pancreatic cancer GPC1 is strongly expressed both by the cancer cells and the adjacent fibroblasts, whereas its expression is low in the normal pancreas (51); in breast cancer GPC1 expression is strong in high-grade tumors (52), whilst in prostate cancer high expression occurs in tumor stroma although it disappears in tumor epithelial cells (53).