UAS regulatory sequences are fused upstream of a sfxa109-flanked cassette carrying hid coding sequences followed by mCherry coding sequences in reverse. 'sfxa109' is the target site for Rci recombinase (see PMID:12054795). In the absence of Rci recombinase, only hid protein is made. In the presence of Rci, the cassette can invert resulting in mCherry expression instead of hid. Can be used to test for the presence of Rci recombinase.