The exu promoter drives expression of a mutated form of exu in which all par-1 phosphorylation sites within 14-3-3 protein binding sites A and B have been mutated; carries amino acid replacements S436A, S437A, S438A, S440A, S456A and S457A.
More than one-third of embryos derived from exuVL/exuXL1 ; exuA6B3 females develop head defects typical of exu mutants.