In prostate tumours, complex changes in proteoglycans occur, with a common trend towards decrease of decorin and lumican expression, overall increase of syndecan-1 and glypican-1 expression in tumour stroma along with its disappearance in tumour epithelial cells, and aggrecan and NG2 expressions in some prostate tumours. The gene discussed is GPC1; the disease is prostate neoplasm.