ELDF15, homologous with AT2 receptor-interaction protein 1 (ATIP1), may play an important role in celldifferentiation, proliferation, and carcinogenesis. We aimed to understand the biological function of ELDF15 viaconstruction and transfection of a recombinant expression vector containing antisense ELDF15. Recombinantexpression vectors were successfully constructed and transfected into K562 cells. A stable transfectant, knownas pXJ41-asELDF15, stably produced antisense ELDF15. Compared with K562 and K562-zeo cells, K562-pXJ41-asELDF15 cells showed inhibition of cell proliferation. RT-PCR analysis showed that the expression andprotein level of ELDF15 decreased significantly in K562 cells transfected with pXJ41-asELDF15. Expressionof hemoglobin increased in K562 cells transfected with pXJ41-asELDF15 by benzidine staining. increases NBTreduction activity in K562 cells transfected with pXJ41-asELDF15.Colony forming efficiency in two-layer softagar was clearly inhibited as assessed by electron microscopy. These results suggest that ELDF15 plays a potentialrole in cell differentiation, proliferation and carcinogenesis.