PKM and breast cancer: Isoform switch from PKM1 to PKM2 and elevated expression of PKM2 have been reported in many types of cancers including glioblastoma, colon and breast cancers [7,8,9,10,11,12,13,14] and is associated with poor prognosis in head and neck cancers, signet ring cell gastric cancer and esophageal squamous cell cancer [11,15,16].