Transcription factor required for smad1 and smad2-mediated responses to TGFbeta during mesoderm induction. Homodimer. Shuttles between nucleus and cytoplasm. Expressed at low levels during early embryogenesis and at highest levels between NF19 and NF28. Expressed in the involuting mesoderm of the gastrula. Expressed in non-neural ectoderm of the early neurula, and excluded from neural plate.