Features:In 2009, Brian Sauer and colleagues cloned the Dre recombinase from phage D6, which can effectively recognize Rox sequences and mediate DNA recombination. The Rox sequence has a similar function and structure to loxP, but with slight differences; it consists of two 14 bp inverted repeat sequences and a 4 bp spacer sequence. Additionally, Cre-loxP and Dre-Rox systems cannot recognize each other, allowing them to be used simultaneously.