The frequency and phenotype of TAS CD8+ T cells were studied in mice bearing CT26 colorectal carcinoma using the well-established MHC class I tetramer loaded with AH1 peptide.25,26 CT26 cells were implanted into the liver to form intrahepatic (IH) tumors and into the skin to form subcutaneous (SQ) tumors (Figure 1A). This evidence concerns the gene CD8A and colorectal carcinoma.