UAS regulatory sequences drive expression of an Tag:HA-tagged Dfd::Scr chimaera. The specificity module (SM) of Dfd is replaced with the analogous region from Scr in the encoded gene product. The region of the Dfd and Scr polypeptides from their YPWM motif through the N-terminal arm of their homeodomain, together with the intervening linker region, is referred to as the SM.