We hypothesized that overexpression of C1GalT1 by tumour cells would change the appearance of short-chain carbohydrate structures such as the unsubstituted TF or Tn and this may alter tumour cell-cell and tumour-stromal cell interactions mediated by the galactoside-binding galectin-3 and GalNAc-binding macrophage lectin (MGL) in the tumour microenvironment (TME), with critical consequence in cancer progression. The gene discussed is C1GALT1; the disease is cancer.