GPC1, known to be highly expressed in pancreatic and breast carcinomas [32,33], was found to be the prevalent GPC of these lesions, alongside with GPC3, which has independently been reported to be up-regulated in several other tumour types and has a recognized value as prognostic factor and putative therapeutic target in hepatocellular carcinomas [34,35,37]. Here, GPC1 is linked to breast carcinoma.