MCFO (MultiColor FlpOut) is a system for multicolor stochastic labeling of cells (Nern et al. 2015). Multiple color combinations are achieved by the use of five different tags (HA, V5, OLLAS, FLAG and Myc) each in a backbone of non-fluorescent GFP (in FlyBase symbols this is referred to as smGdp for 'Green darkened Protein'). Spatial and temporal control of expression is regulated thru the use of one of two binary expression systems (GAL4/UAS or lexA/lexAop) and excision of an intervening stop cassette by one of three recombinases (FLP, B3R or KDR).

Here below is an example of staining in the lamina and medulla from Nern et al. 2015.