Expression of the Assfl allele is not compromised and allows efficient excision.

Panel A: Western blot demonstrating that the loxP sites surrounding exon 13 do not affect ASS expression at the protein level (liver extract with 25µg total protein was loaded per lane; quantification of band intensity on right subpanel). Panel B: ASS protein in ND14 Ass-KO/I mice is eliminated in the enterocytes of the small intestine only. Note that the residual ASS in the small intestine reflects the presence of the ASS-positive enteric ganglia (Figure 2). Light gray bars indicate Ass-Con mice and dark gray bars Ass-KO/I mice (N=4 each).