Expression of the 765bp Hsap\HOXD4 open reading frame is driven by an Hsp70 promoter fragment. 1kb of Dfd trailer/genomic sequence including the polyadenylation site is fused to the 3' end.
Heat induced expression during embryogenesis causes disruption of head involution. Expression during late third instar causes lack of postvertical bristles and reduced ocelli. Also embryos exhibit a Ctx-like transformation of dorsal thoracic bristles in the dorsal posterior head.
Heat induced expression during embryogenesis causes disruption of head involution. Expression during late third instar causes deletion of the ventral eye which is replaced by a rostral membrane and disfigured maxillary palps.