Detection of surface CD49f, a surface integrin (α6) upregulated in HNSCC tumors and also a marker of normal stem cells in various tissues [27], [28], [29], [30], showed that freshly harvested HEp3 cells from tumors or SQ20b and FaDu cells from culture expressed high levels of this integrin (Fig. S1A). Here, ITGA6 is linked to head and neck squamous cell carcinoma.