BTLA and head and neck squamous cell carcinoma: Figure6A-I shows that FRZB expression in HNSCC was obviously related to theabove immune checkpoint genes. It is interesting to note that in HPV-positivepatients with HNSCC, FRZB expression and immunologic checkpoint gene expressionhad a stronger positive correlation, especially CD27 and BTLA. Analysis based onthe GEO database also showed a strong association of FRZB with the above immunecheckpoints (Supplementary FigureS3).