Pyruvate kinase (PK) is a rate-limiting glycolytic enzyme that converts phosphoenolpyruvate (PEP) and adenosine diphosphate, into pyruvate and ATP irreversibly thereby determines glycolytic activity.[8] In tumor cells pyruvate kinase predominantly presents as M2 isoform (PKM2) while normal cells express the M1 isoform (PKM1).[9] Some studies have demonstrated that PKM2 plays an important role in breast cancer. This evidence concerns the gene PKM and breast cancer.