Fig. 1. Expression of activin A signaling components in embryonic mouse pancreas and pancreatic explants. Expression of activin A, follistatin and type I activin receptors ALK2 and ALK4 was assessed by RT-PCR, with TBP mRNA as a reference, on RNA extracted from the pancreas of embryos at the stages indicated (A) or from pancreatic explants cultured for the times (days) indicated (B).