An Hsp70 promoter drives expression of a truncated form of Mmus\Hoxa5 which lacks the homeodomain and part of the carboxyl terminus.
Embryos in which Mmus\Hoxa5Δ.hs is expressed using heat shock are able to hatch and have no cuticle defects. Ectopic expression of Mmus\Hoxa5Δ.hs during the larval stages using multiple heat shocks does not result in transformations.