Fig. 3.

Genetic strategies for lineage analysis. a A transcriptional terminator (STOP) flanked by unidirectional FRT/lox sites blocks the expression of an effector/reporter gene such as GFP. In the cell population expressing Flp/Cre, the recombinase removes the terminator sequence to activate effector/reporter expression. b MARCM uses GAL80 to suppress marker expression driven by the GAL4-UAS binary expression system. The wild-type (WT), but not mutant (MUT), allele of the gene of interest is linked with GAL80. After Flp-mediated mitotic recombination, only the homozygous MUT progeny lose GAL80 and are labelled by marker gene expression. c In the original MADM configuration, N-terminal and C-terminal coding regions of GFP and RFP are segregated on homologous chromosomes. Cre-mediated mitotic recombination reconstitutes these coding regions to generate four distinct types of progeny (GFP⁺ only, RFP⁺ only, GFP⁺/RFP⁺ double-positive and unlabeled), in which fluorescent labeling corresponds to cellular genotype