Cdx2 does not support expression from the <i>Cdx1</i> promoter in the small intestine.

<p>(A) Immunohistochemistry for Cdx1 (i-iii) or Cdx2 (iv-vi) in the small intestine of E18.5 WT (i, iv), <i>Cdx1^2ki/2ki</i> (ii, v) or <i>Cdx1^2ki/2kiCdx2^−/−</i> (iii, vi) animals. Western blot analysis for Cdx1 (B) or Cdx2 (C) and actin loading controls from small intestine. (D) qPCR analysis for transcripts from the <i>Cdx1</i> locus in knock-in animals (red arrows in F) relative to WT (blue arrows in F). (E) qPCR analysis for WT (blue arrows in F) and knock-in (red arrows in F) transcripts from the <i>Cdx1</i> locus heterozygous animals. *P<0.05 by student’s t-test. (F) Schematic representation of the wild type and targeted <i>Cdx1</i> allele with primer sets for measuring WT (blue) and knock in (red) transcripts.