PKM and neoplasm: Through suppressing the expression of PKM2, GLUT1 and LDHA in MCF-7 and MDA-MB-231 cells, quercetin limited the rate of glucose absorption and lactate generation, which in turn modulated the pH of the tumor microenvironment and restricted the energy flow into tumor cells (Jia et al., 2018; Barbosa and Martel, 2020).