IDO1 and neoplasm: The expression of four TME-related genes (CXCL10, LZTS2, IDO1, and MAB21L2) that predict the TME signature of CRC was validated in four GEO datasets: GSE20916 (145 samples), GSE21815 (141 samples), GSE3629 (121 samples), and GSE89287 (71 samples), which contained normal control and tumor samples.