In previous studies, and in the present in vitro model of the stem cell niche, we have shown that polarization and the formation of filopodia may be increased in the CD44+ CXCR4+ HNSCC UM-SCC-11A cell line in a dose-dependent manner using SDF-1 (10,14). Here, CXCL12 is linked to head and neck squamous cell carcinoma.