Cre-Lox recombination is a site-specific recombinase technology, used to carry out deletions, insertions, translocations and inversions at specific sites in the DNA of cells. It allows the DNA modification to be targeted to a specific cell type or be triggered by a specific external stimulus.

Cre (Cre recombinase) is one of the tyrosine site-specific recombinases (T-SSRs) including flipase (Flp) and D6 specific recombinase (Dre) [1,2]. it was discovered as a 38-kDa DNA recombinase produced from cre (cyclization recombinase) gene of bacteriophage P1 [3,4,5,6].

The Cre/loxP system is a widely applied technology for site-specific genetic manipulation in mice. This system allows for deletion of the genes of interest in specific cells, tissues and the whole organism to generate a diversity of conditional knockout mouse strains.

The Cre enzyme identifies pairs of loxP sites (arrowheads), which flank (flox) the DNA, and catalyzes reciprocal DNA recombination between the two sites to excise a small piece of DNA.