Furthermore, the MXE regions of PKM1/PKM2 and of PFKP were found to overlap with pan-cancer mutations in structural regions close to functional sites (Fig 5A and 5B), reinforcing the idea that mutations in these regions impact on the function of the proteins and that cancer mutations tend to have similar effects on function as the effects mediated by MXE variable positions. The gene discussed is PKM; the disease is cancer.