lexAop and UAS regulatory sequences are followed by a minimal heat shock promoter and the E2-Orange fluorescent protein tagged with a nuclear localization signal (Tag:NLS(Unk)). The lexAop and UAS regulatory sequences are flanked by loxP and lox2272 sites respectively (meaning that the P1cre recombinase can be used to excise one of the enhancers in a mutually exclusive manner if desired).