Nevertheless, several studies have further identified a panel of secreted protein including cathepsin D, stroma-associated protein periostin, cytokeratin 18, keratin-8, stathmin-1, L-plastin, galectin-1, S100 calcium-binding protein A9 (S100A9, C-C motif chemokine 5) (CCL5), and chloride intracellular channel 1 (CLIC1) were deregulated in NPC only, thereby suggesting these as potential NPC biomarkers for diagnosis [48,49,51,52,53,54,96,97]. Here, S100A9 is linked to nasopharyngeal carcinoma.