For example, lactic acid produced by cancer cell glycolysis can induce the upregulation of hypoxia-inducible factor-1 alpha (HIF-1α) in TAM, thereby enhancing the expression of glycolysis gene and M2-like state, thereby promoting tumor progression, angiogenesis and epithelial-mesenchymal transformation (EMT) (Colegio et al. 2014). Here, HIF1A is linked to cancer.