Wnt Inhibitory Factor 1 (WIF1) is a secreted protein, which binds WNT proteins and inhibits their activities. WNT proteins are extracellular signaling molecules involved in the control of embryonic development. WIF1 contains a WNT inhibitory factor (WIF) domain and 5 epidermal growth factor (EGF)-like domains. is found to be present in fish, amphibia and mammals. WIF1 is a recurrent target in human salivary gland oncogenesis.WIF1 may be involved in mesoderm segmentation. WIF1 is a tumor suppressor, specifically in nonfunctioning pituitary tumors.