Primers are designed to amplify sequences present only in the vector backbone. If a correct homologous recombination has occurred then no product should be amplified. If a product is detected it strongly suggests an incorrect targeting event or a multiple insertion event.

Not all vector primers will be present in all backbones – please refer to the tables below on which primers to use. 

Please note that the absence of a product does not necessarily prove that the targeting is correct and this test should be used in conjunction with others