NPM1 and acute myeloid leukemia: In fact, it has been suggested that the nucleoli of NPM1 mutated AML cells might be particularly susceptible to drugs that induce a nucleolar stress response due to the partial depletion of NPM1 caused by both haploinsufficiency and retention of a fraction of NPM1wt by NPM1c+ in the cytoplasm (Falini et al., 2015).