Fig. 1.

Dab2 is required for suppression of c-Fos expression in endoderm cells derived from differentiation of ES cells. (A) ES cells were treated with or without 1 µM retinoic acid (RA) for 3 days to induce endoderm differentiation. The cells were then cultured without serum for 18 hours +/− RA, stimulated with 15% serum for 90 min, and fixed for immunostaining for Dab2 (red), c-Fos (green), or DAPI staining (blue). (B) On day 1, ES cells were transfected with siRNA-Dab2 vector and simultaneously treated with or without RA for 3 more days. The cells were cultured in medium containing low serum (1%) over night and were then stimulated with 10% serum for 90 min and fixed for immunostaining for Dab2 (green), c-Fos (red), or for DAPI (blue). The cell numbers with various combinations of Dab2 and C-Fos expression were counted based on these images, and were used for statistical analysis as summarized in Table 1. (C) Dab2 (red) and c-Fos (green) expression in RA-treated ES cells transfected with the Dab2-siRNA suppressing vector. The cells are a mixture of with (arrow) or without (arrowhead) transfection/Dab2 suppression.