Lactic acid, a byproduct of glycolysis, accumulates in tumor microenvironment (TME) and causes extracellular acidification, thereby promoting the polarization of tumor-associated macrophages (TAM) towards an M2-like phenotype, which in turn secrete immunosuppressive and pro-angiogenic factors such as transforming growth factor-beta (TGF-β), interleukin-6 (IL-6) and VEGF. This evidence concerns the gene TGFB1 and neoplasm.