Figure 4.

BMPs are necessary for primary hepatic induction. (A) Explants of foregut endoderm and cardiac mesoderm were isolated at the designated time points and assayed for albumin expression by RT–PCR. (B) RT–PCR data demonstrate the elevation of pdx-1 expression simultaneously with the suppression of albumin expression, in noggin-treated cultures, compared with the control. (C) RT–PCR data of endoderm cultured alone demonstrate that BMP and TGFβ2 were not efficient inducers of albumin gene expression in cultures of ventral foregut endoderm in the absence of cardiac mesoderm, whereas FGF2 was efficient.