The NPM1 locus is involved in translocations associated with hematologic malignancies, including (i) acute promyelocytic leukemia t(5;17)(q35;q12) leading to NPM1-RARα (retinoic acid receptor alpha fusion protein), (ii) anaplastic large cell lymphoma t(2;5)(p23;q35) leading to NPM1-ALK (anaplastic lymphoma kinase fusion protein), and (iii) myeloid neoplasms t(3;5)(q25;q35) leading to NPM1-MLF1 (myeloid leukemia factor 1 fusion protein) [54,55]. This evidence concerns the gene MLF1 and acute promyelocytic leukemia.