Z-DNA binding protein 1 (ZBP-1) belongs to a family of proteins that contain the Zalpha domain, which binds specifically to left-handed Z-DNA and Z-RAN. Vertebrate ZBPs are induced by immunostimulation and are involved in host defense mechanisms. ZBP-1 initiates an innate immune response by binding to foreign DNA in the cytosol. ZBP-1 mediates activation of the innate immune system by facilitating DNA-mediated induction of type-1 IFN and expression of other related genes. Human ZBP-1 is most prominently expressed in lymphatic tissues. Besides its function in immunoresponse, it is up-regulated in mouse tumor stromal cells and is speculated to play a role in host defense again tumors.