A genomic fragment that encompasses the entire E(spl)-complex, but in which the E(spl)m3-HLH open reading frame has been deleted and replaced by the sfGFP coding region. The E(spl)mδ-HLH and E(spl)mβ-HLH open reading frames have each been flanked by a pair of FRT sites, so that they can be excised in the presence of FLP.