Since lactate, the product of PKM2 in glucose metabolism, could facilitate macrophages polarization toward M2 macrophage, which could inversely affect the neoplastic cells via the secretion of bioactive factors, leading to a more aggressive phenotype14, 15, we postulated that PKM2-resultant lactate favors M2 macrophages, which then inversely affect the cancers cells so as to promote the disease progression (Figure 5). This evidence concerns the gene PKM and cancer.