However, due to the reduced expression of transporters associated with TAP1, which is associated with antigen processing in HNSCC cells, cytotoxic T cells may be resistant to pathogens or cancer cells because they lack the essential signals to identify and eliminate these abnormal cells.166, 167, 168 Consequently, when the integrity of the tumor MHC-I APM is compromised, it results in the accumulation of MHC-I in the cytoplasm awaiting degradation and reduces the amount of MHC-I transported to the cell membrane.169. Here, TAP1 is linked to head and neck squamous cell carcinoma.