UAS regulatory sequences and a minimal Hsp70 promoter are fused upstream of a fusion protein that consists of an ScFv that binds Tag:HA (scFv(antiHA-12CA5)), a transmembrane domain (Tag:M(mCd8a)) and the mCherry fluorescent tag. The scFv(antiHA-12CA5) ScFv is extracellular, allowing it to trap any Tag:HA-tagged extracellular protein, while the mCherry tag is located in the cytosol. (Generated by P1cre-mediated excision of the lexAop regulatory sequences present in Zzzz\scFvlexAop.UAS.HAtrap.ext.mCherry).