PFKM and neoplasm: Tumor cells, including PDAC cells, preferentially express HK2, an isoform of the HK family that localizes to the outer membrane of mitochondria and other sites in the cell.226 Furthermore, PDAC, like other gastrointestinal cancers, depends on increased activity of rate-limiting enzymes in the glycolytic pathway,227 including phosphofructokinase isoenzyme 1 (PFK1) and pyruvate kinase isoenzyme 2 (PKM2), which are expressed in many tumor cells, including those in PDAC.