Fig. 8. The 50 bp element is required for lab550 activity. 92/394m300 was not active in wild-type embryos (D), while the same enhancer containing the 50 bp element (92/444m300) was active both in the endoderm of the gastric caeca and adjacent to ps7 (A). Mutation of either the GATA- (G) or the HMG- (H) binding site in 92/546m300 resulted in strongly reduced expression. In the absence of the mutation in the putative repressor binding site 300 and in the presence of the HOMRE, expression of the construct that lacked 50 bp (1/394) was weak in wild-type embryos (E) and inactive in abd-A mutants (F). Expression driven by 1/444 was strong in wild-type embryos (B) and expanded in abd-A mutants (C). Expression of a minimal enhancer construct (1/140;243/444) was also strong in wild-type embryos (I) and strong and posteriorly expanded in abd-A mutants (data not shown).