For instance, the basal-like subtype of breast cancer exhibited the highest PPIH expression; in head and neck squamous cell carcinoma, expression was significantly higher in HPV-positive cases than in HPV-negative ones; and in gastric cancer, the genomically stable (GS) subtype showed the lowest PPIH expression (Figures 2E–J). This evidence concerns the gene PPIH and head and neck squamous cell carcinoma.