lexAop and UAS regulatory sequences and a minimal Hsp70 promoter (derived from the pUASTLOTattB vector) are fused upstream of dpp that is tagged with EGFP downstream of the second predicted furin cleavage site. 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).