NOS2 and neoplasm: Different from mouse tumor-infiltrating MDSCs, the expression of ARG1 and NOS2 was not detected in MDSCs (or in any types of tumor-infiltrating leukocytes, Supplementary Fig. 7i) from CRC patients, but the expression of other functional genes, like IL10 and VEGFA that facilitate tumor development, was upregulated in the process of MDSC ‘differentiation’ (Supplementary Fig. 7i).