- Hgs (Hrs), a FYVE domain protein, is involved in Smad signaling through cooperation with SARA. Miura, S., Takeshita, T., Asao, H., Kimura, Y., Murata, K., Sasaki, Y., Hanai, J.I., Beppu, H., Tsukazaki, T., Wrana, J.L., Miyazono, K., Sugamura, K. Mol. Cell. Biol. (2000)