Mammalian homologs of the Drosophila Mad gene include Smad1, Smad2, Smad3, Smad4 (DPC4), Smad5, Smad6, Smad7 and Smad8. Smad1 and Smad5 are effectors of BMP2 and BMP4 function while Smad2 and Smad3 are involved in TGF and activin-mediated growth modulation. Smad4 has been shown to mediate all of the above activities through interactionwith various Smad family members . Smad6 and Smad7 regulate the response to activin/ TGF signaling by interfering with TGF -mediated phosphorylation of other Smad family members. This antibody is a mouse monoclonal antibody raised against an internal region of human SMAD4.