A chromosomal aberration involving CCDC28A has been identified in acute leukemias. Translocation t(6;11)(q24.1;p15.5) with NUP98. The chimeric transcript is an in-frame fusion of NUP98 exon 13 to CCDC28A exon 2. Ectopic expression of NUP98-CCDC28A in mouse promotes the proliferative capacity and self-renewal potential of hematopoietic progenitors and rapidly induced fatal myeloproliferative neoplasms and defects in the differentiation of the erythro-megakaryocytic lineage. It is uncertain whether Met-1 or Met-91 is the initiator. The first 90 residues are not conserved and orthologous sequences, including rat and mouse ones, contain a stop codon upstream of the conserved methionine.