Cell surface-associated PGs are differentially expressed in primary lesions of oral cavity HNSCC patients. (a) Heat map and hierarchical clustering of the relative expression levels (columns) of the 8 most modulated cell surface-associated PGs in primary lesions of 119 oral cavity HNSCC patients (rows): red, up-regulation; green, down-regulation, black: no change in comparison to the healthy epithelial tissue. Distance between clusters was calculated as reported in Additional file 3. (b) PG expression profiles in oral cavity HNSCC specimens derived from T1-T2-N-, T1-T2-N+, T3-T4-N- and T3-T4-N+ graded tumours. SDC1-4, syndecans 1–4; GPC1-6, glypicans 1–6.