Calprotectin or S100A8/A9, a heterodimeric complex of calcium-binding proteins S100A8 (MRP8 or calgranulin A) and S100A9 (MRP14 or calgranulin B), may play a role in growth regulation and tumorigenesis in HNSCC and other squamous cell carcinomas (SCCs). Here, S100A9 is linked to head and neck squamous cell carcinoma.