PKM and cancer: When testing enzymatic activity of glycolytic enzymes and extracellular concentrations of lactate in four murine cancer cell lines (i.e., L1210—lymphocytic leukemia, 4T1—breast, B16—murine melanoma and CT26—colon), it was demonstrated that cells exposed to curcumin have a significant decrease of activity of hexokinase, lactate dehydrogenase, phosphofructokinase and pyruvate kinase (which may indicate the switch from active PKM1 to less active PKM2—which will be discussed later), in all but melanoma-originating B16.