Figure 4.
Phosphorylation and nuclear translocation of Smad-1 occurs when either isolated crest- or noncrest-derived cells are exposed to BMP-2 or BMP-4. Crest- and noncrest-derived cells were isolated from the fetal bowel at E12 by positive and negative immunoselection with antibodies to p75NTR. A, Isolated crest-derived cells exposed to BMP-4. Smad-1P immunoreactivity is strikingly evident in the nuclei of subsets of process-bearing cells (arrows). B, Isolated crest-derived cells exposed to vehicle. No Smad-1P immunoreactivity is discernible in the nuclei of process-bearing cells (arrows). C, Isolated crest-derived cells exposed to BMP-4 and noggin. The addition of noggin has inhibited the effect of BMP-4 (compare with A; see also L). D-G, Isolated noncrest-derived cells exposed to BMP-2. Cells developing in a smooth muscle lineage are marked by the immunocytochemical demonstration of SMA. D, Smad-1P immunoreactivity. E, SMA immunoreactivity. F, Merged image (Smad-1P/SMA immunoreactivities). G, Bisbenzamide (DNA). Smad-1P immunoreactivity is strikingly evident in the nuclei of subsets of SMA-immunoreactive cells (arrows). H-K, Isolated noncrest-derived cells exposed to vehicle. H, Smad-1P immunoreactivity. I, SMA immunoreactivity. J, Merged image (Smad-1P/SMA immunoreactivities). K, Bisbenzamide (DNA). No immunoreactivity is discernible in the nuclei of SMA-immunoreactive cells (arrows).