While on one hand PIN1 can promote nuclear retention of CYCLIN D1 (39) and NF-kappaB (69) proteins, it induces a direct change in protein subcellular localization of some substrates, as in the case of Pyruvate Kinase 2 (PKM2), whose association with Importin alpha5 and its consequent nuclear translocation, a crucial step in the activation of the Warburg effect in cancer cells, is promoted by PIN1 (76). The gene discussed is PKM; the disease is cancer.