Figure 1.

Schematic illustration of Homologous Recombination by the Flp-In^™ System. Two expression cassettes for heavy and light chains were inserted into pcDNA5/FRT to form vector FV. Vector pOG44 contained the Flp recombinase gene. After co-transfection of both vectors FV and pOG44, the Flp recombinase expressed from pOG44 catalyzes a homologous recombination event between the FRT sites of the Flp-In host cell and the vector FV. Then the whole vector is inserted by homologous integration into the genome of the host cell only at the location of FRT.