Fig. 1. Analysis and representative results from the GIfT expression survey. (A) Group breakdown of TFs according to temporal variation in the developing intestine; the fetal stomach showed virtually identical grouping. All RT-PCR data were quantified; classifications were derived computationally and verified manually. (B) Arbitrary examples from hundreds of TF mRNAs with constant levels during GI organogenesis. The data represent electrophoretic bands of RT-PCR products from our TF survey. (C) RT-PCR results of temporal modulation of TF transcripts during GI organogenesis, highlighting the similar trends observed for most TFs in the intestine and stomach. (D) Statistical analysis of differential gene expression. Most TF mRNAs are expressed either constitutively or with the same temporal variation in both stomach and intestine, and more than 18% of transcripts are not expressed in either site. Only 8% (103 TFs) meet criteria for differential expression between intestine and stomach, including the examples shown in E and F. (E) Selected examples from 25 TF mRNAs that are restricted to the developing stomach (grouped beside the red bar) or intestine (grouped by the blue bar). (F) Examples of TF transcripts that differ between stomach and intestine in pattern but not in absolute expression. The full set of original data can be analyzed at