To further confirm the ST results (transcriptomic level) at the proteomic level, we performed multiplex immunofluorescence (mIF) of both canonical APC markers (MHC-II+) and selected markers for P-Tex cells (CD8+PD1+CDK4+/MKI67+), bulk Tex cells (CD8+PD1+CDK4-MKI67-) and bulk CD8+ T cells (CD8+) on formalin-fixed paraffin-embedded (FFPE) tissue originating from HNSCC patients (Figure 7a–b). Here, MKI67 is linked to head and neck squamous cell carcinoma.