LAUSR

Myelodysplasia/myeloid leukemia factor 1‐interacting protein (MLF1IP) appears to be an erythroid lineage‐specific gene in mice; however, its role in normal erythropoiesis and erythropoietic disorders have not yet been elucidated. Here, we found that MLF1IP is abundantly expressed in human erythroid progenitor cells and that MLF1IP‐deficiency reduces cell proliferation resulting from cell cycle arrest. Moreover, MLF1IP expression is exclusively elevated in CFU‐E cells from polycythemia vera (PV) patients, and MLF1IP transgenic mice develop a PV‐like disorder. Further analyses revealed that the erythroid progenitors and early‐stage erythroblasts from these transgenic mice expand by up‐regulating cyclin D2 and down‐regulating p27 and p21. Thus, our data demonstrate that MLF1IP promotes erythroid proliferation and is involved in the pathogenesis of PV, suggesting that it might be a novel molecular target for erythropoietic disorders.