SENP6 and leukemia: Moreover, we observed decrease and increase of SUMOylation of exogenous PKM2 by ectopically expressing sentrin/SUMO-specific protease 1 (SENP1) (Fig. 1B), or SUMO1 (Fig. 1C) in NB4 leukemia cell lines respectively, suggesting that PKM2 is a SUMOylated protein in leukemia cells.