CLDN1 and colorectal carcinoma: Figure 3 shows the IHC findings of seven common cancer antigens and HLA class I for two representative cases from 14 patients with primary CRC and liver metastases. In one representative case (Case 6), HLA class I exhibited low expression levels in both primary CRC and liver metastases. Conversely, high expression levels of CLDN1 and LAT1 were observed in both primary CRC and liver metastases. MFIH analysis (Figure 4) visually confirmed the low HLA class I expression and high CLDN1 and LAT1 expression in the primary tumor.