P{CoinFLP-GAL4} carries overlapping FRT and FRT3 cassettes. FLP recombinase can induce recombination between FRT or FRT3 pairs, but FRT and FRT3 are incompatible. When FLP is expressed, one cassette or the other is removed stochastically. Removal of the FRT cassette allows GAL4 expression.

P{CoinFLP-LexA.GAL4} is a similar construct where LexA is expressed upon removal of the FRT cassette and GAL4 is expressed upon removal of the FRT3 cassette.

If P{CoinFLP-LexA::GAD.GAL4} is combined with the split GFP constructs P{UAS-CD4-spGFP1-10} and P{lexAop-CD4-spGFP11}, the interface between the two kinds of clones will be marked with GFP.

These constructs and methods are described in Bosch et al. (2015) "CoinFLP: A system for efficient mosaic screening and for visualizing clonal boundaries in Drosophila" Development 142: 597-606.

Stocks originating in this work are shown below.