In either a wild type or an exd mutant background, heat shock of the embryo causes failure of head involution and a T1 to T2 transformation.
Ectopic expression in embryos causes a phenotype very similar to that of Antphs.PHTA. Phenotype differs in that formation of the thoracic segment specific sensory organs (Keilin's organ and ventral pits) is suppressed. Parasegments have a mixed identity, denticle belt phenotype has an Antp-like parasegment 4 identity but the suppression of thoracic segment specific sensory organs has a Ubx-like parasegment 6 identity. Heat shock of the construct in Antp25 embryos displays 100% transformation of thoracic and head parasegments.