Mice with a targeted Flt3ITD mutation develop myeloproliferative neoplasms (MPN) (Lee et al., 2007; Li et al., 2008), and several other mutations (e.g. Npm1, Tet2 and Runx1 mutations) cooperate with Flt3ITD to drive AML in mice much as in humans (Mead et al., 2013; Mupo et al., 2013; Rau et al., 2014; Shih et al., 2015). Here, NPM1 is linked to acute myeloid leukemia.