PKM and plasma cell myeloma: To further investigate whether NEK2 has a synergistic or additive effects in patient outcome, the 351 myeloma patients were classified into 4 groups including low-NEK2/low-PKM2, low-NEK2/high-PKM2, low-PKM2/high-NEK2, and high-NEK2/high-PKM2; and Kaplan-Meier analyses showed clearly that the high NEK2/PKM2 group had the worst outcome in both EFS and OS (Fig. 4e).