Fig. 6. Limb abnormalities induced by dHAND mutant proteins that fail to bind DNA. (A) Amino acid sequence of the basic regions of wild-type and mutant dHAND proteins. X designates residues that were deleted in the basic mutant. (B,C) F₀ transgenic mouse embryos harboring prx-RRR109EDE (B) and prx-basic (C) transgenes, respectively, were sacrificed at E16.5 and limbs were stained for bone and cartilage. Both constructs induced preaxial polydactyly, as well as truncation of the zeugopod. Both panels show forelimbs. Ectopic digits are indicated with an asterisk. Arrowheads indicate zeugopod abnormalities.