Cre-mediated recombination between MICER clones MHPP256h04 (13:78,918,316; MM9) and MHPN5k06 (13:79,454,030; MM9) that restores a functional Hprt gene and generated a megadeletion (MD) of 535 Mb containing the orthologous region to the rat mammary carcinoma susceptibility locus Mcs1a. (J:199158)