Lhx2, a vertebrate homologue of apterous, regulates vertebrate limb outgrowth

apterous specifies dorsal cell fate and directs outgrowth of the wing durin g Drosophila wing development. Here we show that, in vertebrates, these fun ctions appear to be performed by two separate proteins, Lmx-1 is necessary and sufficient to specify dorsal identity and Lhx2 regulates limb outgrowth . Our results suggest that Lhx2 is closer to apterous than Lmx-1, yet, in v ertebrates, Lhx2 does not specify dorsal cell fate. This implies that in ve rtebrates, unlike Drosophila, limb outgrowth can be dissociated from the es tablishment of the dorsoventral axis.