SIGLEC1 and cancer: Glycosyltransferase alterations could change the nature of the TME and reverse adverse characteristics of TME cells, altering a “cold tumor” into a “hot tumor.” For example, the changed glycosyltransferase motifs on Mucin 1 (MUC1) could promote cancer immune surveillance by interacting with CD169, which enhances macrophage activation after binding to sialylated MUC1 and promotes tumor growth (Reily et al., 2019).