lexAop and UAS regulatory sequences and a minimal Hsp70 promoter are fused upstream of a fusion protein that consists of DARPin 1242_F1 (an artificial protein sequence that specifically binds dpp protein), a transmembrane domain (Tag:M(mCd8a)) and the mCherry fluorescent tag. The DARPin sequence is extracellular, allowing it to trap extracellular dpp protein, while the mCherry tag is located in the cytosol. The lexAop and UAS regulatory sequences are flanked by loxP and lox2272 recombinase target sites respectively (meaning that the P1cre recombinase can be used to excise one of the enhancers in a mutually exclusive manner if desired).