In euakryotes, mRNAs must be exported from the nucleus to the cytsoplasm. NXF2 is highly expressed in the mouse male germ cells. We are interested in its function in spermatogenesis, espically in the nuclear RNA export in the testis. To this end, we made Nxf2 mutant mice by gene targeting. In an attempt to identify the mRNA substrates of NXF2, we perform the microarray experiments on testes.