Although early reports have indicated that the PKM2 isoform is specifically expressed in the tumor, a recent study from a survey of 16 human normal adult tissues and cancer samples has demonstrated that both PKM1 and PKM2 isoforms exist in normal tissues while PKM2 is the dominant isoform in both normal and cancers in majority of tissues, albeit with a more obvious enrichment of PKM2 in the cancer samples [31]. The gene discussed is PKM; the disease is cancer.