STIP1 and ovarian cancer: STIP1 is a cochaperone that organizes other chaperones [45], and it has been recently described to be secreted by human ovarian cancer cells; whereas PNPO catalyzes the oxidation of pyridoxine 5′-phosphate to pyridoxal 5′-phosphate, the active cofactor form of vitamin B(6) required by more than 140 different catalytic activities [46].