Analyses of the relative mRNA expression levels of the eleven prevalent cell surface-associated PGs conducted on a total of 119 primary oral cavity HNSCC lesions revealed that 3 of the PGs, including NG2/CSPG4, GPC2 and GPC5, were de novo expressed in neoplastic cells, i.e. were not detectable in the healthy control tissues, but were detectable in cancer cells. This evidence concerns the gene GPC5 and cancer.