Mammalian genomes contain 2 PUF genes: pum1 and pum2. The members of the PUF family regulate development in a variety of species. PUF proteins contain a C-terminal RNA-binding domain known as Pumilio homology domain (PUM-HD), and these proteins influence mRNA stability and translation by specifically binding to 3′UTR of the target mRNA. PUM2 gene contains 20 exons and is localized at 2p23-24. RT-PCR analysis indicated that PUM2 was abundantly expressed in embryonic stem (ES) cells, ovary, and testis. PUM2 was found to be expressed predominantly in human ES cells and germ cells, and it was colocalized with DAZ and DAZL, which are RNA binding proteins (RBPs) that function in the early germ line stem cells. Therefore, PUM2 may be required for germ cell development. Recent studies have shown that PUM2 represses the expression of mitogen-activated protein kinase 1 (MAPK1) and MAPK14 in human ES cells and in the Caenorhabditis elegans germline cells by binding specifically to FBF binding elements (FBEs) within the 3′UTR of the target mRNAs.