To prove that NPM1mut directly causes HOXA and HOXB overexpression as opposed to it being a consequence of stalled differentiation, Brunetti and colleagues used CRISPR-Cas9 gene editing to interrupt the NES in NPM1 mut resulting in nuclear re-localisation and subsequent differentiation and arrest in AML cells, showing that HOX gene overexpression is facilitated by NPM1mut. This evidence concerns the gene NPM1 and acute myeloid leukemia.