Fig. 7. The mosaic analysis with a repressible cell marker (MARCM) technique. Both Gal80 and Gal4 expression is driven using tubulin promoters (tub). In the parent cells, the Gal80 inhibits the activity of Gal4. Mitotic recombination creates a clone of homozygous mutant cells that lack the tub-Gal80 construct. The Gal4 generated by the tub-Gal4 construct (purple) is now free to drive expression from the UAS-gene construct (blue).