PTGIR and head and neck squamous cell carcinoma: The selection process, depicted in Fig. 4a, resulted in the following two types of validation candidates: (1) those highly expressed in both HPV+ and HPV− HNSCC: LY6K, and (2) those preferentially expressed in HPV+ HNSC: ROR2, VCAM1, ICAM1, ITGA2B, PTGIR, and CELSR3.