CTLA4 and head and neck squamous cell carcinoma: To further explore the impact of SAR1A on the immune microenvironment in HNSCC, we applied the TIMER software http://timer.cistrome.org/ (accessed on 6 August 2024) to investigate the association between SAR1A and key immune checkpoints, such as CD274 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) (Figure 2D).