Exhibits arylsulfatase activity and highly specific endoglucosamine-6-sulfatase activity (PubMed:12368295, PubMed:12686563). It can remove sulfate from the C-6 position of glucosamine within specific subregions of intact heparin (PubMed:12368295, PubMed:12686563). Diminishes HSPG (heparan sulfate proteoglycans) sulfation, inhibits signaling by heparin-dependent growth factors, diminishes proliferation, and facilitates apoptosis in response to exogenous stimulation (PubMed:12686563). . This is the function of Ensembl gene identifier ENSG00000137573 (SULF1, sulfatase 1).