Other proteins have already been associated with HNSCC by several authors [44–46] and by our group, particularly annexin A1 [47, 48], fatty acid-binding protein E-FABP [49, 50], heat shock protein beta-1 [51, 52], galectin-1 [53, 54], glutathione S-transferase P [55, 56], keratin, type I cytoskeletal 13 [57, 58], peptidyl-prolyl cis-trans isomerase A [59, 60], periostin [61], protein deglycase DJ-1 [62, 63], protein S100A7 [64, 65] and Ras-related protein RAP-1A [66]. Here, PPIA is linked to head and neck squamous cell carcinoma.