PKM and cancer: PKM2 has diminished activity compared to PKM1, thus slowing down the last reaction of the glycolytic pathway, which may look disadvantageous, but indeed is beneficial to cancer cells, since decreasing the speed of the last steps of glycolysis increases the flux of glycolysis intermediates to PPP, thus generating more NADPH and precursors for nucleotide biogenesis like ribose-5-phosphate [20–22].