Figure 1.

Lineage tracing and usage of Cre-lox-mediated site-specific recombination. (A) Basic outline of lineage tracing. “Cell-identifier” of various kinds are introduced in selected cells (red), that are inherited by the daughter cells. “Cell-identifier”-tagged cells (red) at later stages of life are identified as the progenies of these initially tagged cell(s). (B,B′) Cre-lox recombination system is commonly used for lineage tracing. Cell-specific transcriptional drivers, inducing expression of Cre recombinase allows recombination between loxP sites, which in turn results in expression of a reporter gene. The progenies of these cells (in green), also expressing the reporter, can be identified at different stages of life.