Brainbow techniques rely on the Cre-Lox recombination, in which the protein Cre recombinase drives inversion or excision of DNA between loxP sites. The original Brainbow method includes both Brainbow-1 and Brainbow-2, which utilize different forms of cre/lox recombination. Brainbow-3, a modified version of Brainbow-1, was developed in 2013.[5] For all Brainbow subtypes, the expression of a given XFP is a stochastic, or random, event.