Short-term BMP-4 treatment induces mesoderm progenitors in hES cells. (A) Q-PCR analyzes profiles of several other genes during hES cell differentiation in the presence of BMP-4 (B25). WNT3 and MIXL1, expressed in the mesendoderm and mesoderm, both had similar expression pattern to brachyury. However, GSC and FOXA2, expressed in the mesendoderm and endoderm, were not induced during this process. In this study, hES cell differentiation by 100 ng/mL activin A treatment (A100) was used as a positive control for mesendoderm and endoderm gene expression.⁵⁶  Numbers on the x-axis indicate days of differentiation; numbers on the y-axis indicate relative gene expression level normalized to that of GAPDH. Error bars indicate standard deviations. (B) Immunocytochemistry results showed that, at day 1 of differentiation, when brachyury displayed high level expression, no GSC or FOXA2 expression could be detected. Scale bars represent 50 μm.