Cre Recombinase is a tyrosine recombinase enzyme derived from the P1 Bacteriophage. The enzyme uses a topoisomerase I like mechanism to carry out site specific recombination events. The enzyme (38kDa) is a member of the Integrase family of site specific recombinase and it is known to catalyse the site specific recombination event between two DNA recognition sites (loxP sites).This premade lentivirus expresses Cre under the control of the tetracycline-responsive element (TRE). It also coexpresses rtTA and hygromycin under the control of the PGK promoter. Cre expression can be induced by doxycycline.