Fig. 6. Hoxd and Gli3 limb expression suggest a quantitative model for modification of Gli3 repressor function by total Hoxd10/11/12/13 protein expression. Schematics show the expected gradient of Gli3:[total Hoxd] complexes across the limb bud AP axis at early (left) and late interdigit (right) stages, and possible Gli3-regulated processes that may be affected by the varying Gli3-Hoxd stoichiometry across the limb bud. This model is compatible with the known functional overlap, and the incremental additive effects of posterior Hox genes in regulating digit morphogenesis (e.g. Zakany et al., 1997).