The guanylate-binding proteins (GBPs), a family of interferon-induced GTP-binding proteins function in innate immunity against microbial and viral pathogens. In humans, there are seven GBPs from hGBP1 to hGBP7. Human GBP1 and GBP2 have been shown to exhibit antiviral activity as well as being able to regulate the inhibition of proliferation and invasion of endothelial cells in response to interferon (IFN) (1,3). GBP6 is induced by IFN and hydrolyzes GTP to both GDP and GMP. The precise function of GBP6 is still under investigation .