Drosophila Sog and vertebrate Noggin play important roles during development. They function as antagonists against BMP4 signaling and induce neural ectoderm during embryogenesis. They are also engaged in appendage formation by inhibiting BMP4 signaling during late development. To understand further functions of Sog, Supersog, which is a more potent form of Sog, and Noggin BMP4 antagonists during development, I performed the molecular genetic analysis using Drosophila embryogenesis and wing formation as assay systems. In cellular blastoderm embryos, Sog inhibited Dpp signaling, Drosophila BMP4 signaling, whereas Supersog or Noggin did not block Dpp signaling. During wing formation, Sog inhibited Sax type I receptor of Dpp signaling whereas Noggin inhibited Tkv type I receptor of Dpp signaling. However, Supersog inhibited both Sax and Tkv type I receptors. These results suggest that functions of BMP4 antagonists are developmental stage dependent and indicate that each BMP4 antagonist inhibits BMP4 signaling by blocking different BMP4 receptors.