Fig. 5. Relation between Isx and the gut homeotic regulator Cdx2. (A) Representative RT-PCR analysis of 15 late-activated, intestine-restricted TFs in the stomach of FoxA3-Cdx2 transgenic mice. Isx is the only tested transcript present in the metaplastic stomach. (B) Isx mRNA shadows that of the intestine regulator Cdx2 in time and space. Both TFs are virtually absent from stomach and are activated simultaneously between E11 and E13 in developing mouse intestine (top, RT-PCR analysis); concentration of both mRNAs is highest in adult ileum and cecum (bottom, northern analysis). GAPDH or 28S RNA serve as loading controls. (C) Forced expression of GFP-tagged Cdx2 in fetal mouse stomach explants (left, organ margin outlined in white) consistently induces ectopic expression of Isx mRNA (right, RT-PCR analysis).