We found that CTL4 was overexpressed by 1.399-fold (95% CI 1.044–1.873) in MSI tumors compared to corresponding normal colon tissues, whereas there was non-significant change in MSS tumors, perhaps indicating a potential beneficial effect of the CTL4 inhibitor, such as ipilimumab, in MSI CRC only. The gene discussed is SLC44A4; the disease is colorectal carcinoma.