text: * Vg1 Family
  * Activin Family
  ** Involved in embryogenesis and osteogenesis
  ** Regulate insulin and pituitary, gonadal, and hypothalamic hormones
  ** Nerve cell survival factors 
  **3 Activins: Activin A, Activin B and Activin AB.
  * Glial-Derived Neurotrophic Factor (GDNF)
  ** Needed for kidney and enteric neuron differentiation
  * Müllerian Inhibitory Factor
  ** Involved in mammalian sex determination
  * Nodal 
  ** Binds to Activin A Type 2B receptor
  ** Forms receptor complex with Activin A Type 1B receptor or with Activin A Type 1C receptor.
  *Growth and differentiation factors (GDFs)