<unk>  As with other members of the superfamily,<unk> s interact with two types of cell surface transmembrane receptors (Types I and II) which have intrinsic serine/threonine kinase<unk> ies in their cytoplasmic domains: *<unk>  type 1 receptors: ACVR1, ACVR1B, ACVR1C *<unk>  type 2 receptors: ACVR2A, ACVR2B<unk>  binds to the Type II receptor and initiates a cascade reaction that leads to the recruitment, phosphorylation, and activation of Type I<unk>  receptor. This then interacts with and then phosphorylates SMAD2 and SMAD3, two of the cytoplasmic SMAD proteins. Smad3 then translocates to the nucleus and interacts with SMAD4 through multimerization, resulting in their modulation as transcription factor complexes responsible for the expression of a large variety of genes.<unk>  In contrast to<unk> , much less is known about the mechanism of action of<unk> , but may involve competing with<unk>  for binding to<unk>  receptors and/or binding to<unk> -specific receptors.
Activin and inhibin
Estrone/progesterone/testosterone
Estradiol/progesterone
Estrone/progesterone
SUSPUP and SUSPPUP
Estradiol/estrone/estriol
UPMC Central Pa
IPP-SHR