MRC1 and neoplasm: Elevated expression of Tnf and Nos2 and reduced expression of Chil3, Mrc1, and Arg1 were observed in the BMDMs cocultured with C1galt1 knockout tumor cells, compared with those in the Mock tumor cells (Fig. 2B), suggesting that O‐glycan truncation in tumor cells induced the M1 polarization of cocultured BMDMs.