PLAC1 and head and neck squamous cell carcinoma: According to our previous study, Plac1 is associated with the immunosuppressive microenvironment of HNSCC.[24] To further investigate how Plac1 expression affects the immune microenvironment, we performed immunofluorescence (IF) staining of Tregs and exhausted CD8+ T cells, two key immunosuppressive cells in tongue tissues of Plac1‐CKO and Plac1‐WT mice.