The HRN™ mouse was developed in the laboratory of C. Roland Wolf of the Ninewells Hospital & Medical School. The model was created by targeting the Por gene to generate a floxed allele in GK129/1 embryonic stem cells derived from 129P2 mice and injecting the targeted cells into C57BL/6 blastocysts. Resultant chimeras were backcrossed to C57BL/6 for one generation. Mice heterozygous for the floxed Por allele were intercrossed to generate mice homozygous for the floxed Por allele on a mixed B6;129P2 background. The Alb-cre transgene was developed in the laboratory of Mark A. Magnuson at Vanderbilt University School of Medicine by microinjecting Cre recombinase gene under the control of the rat albumin enhancer/promoter into B6D2F2 zygotes. Mice homozygous for the floxed Por allele were bred to carriers for the Alb-cre transgene to generate HRN™ mice. The HRN™ model was backcrossed to C57BL/6J a total of 6 generations (N6). Taconic received stock from CXR Biosciences in April 2007. The mice were backcrossed to C57BL/6NTac (N7) and embryo transfer derived. The colony was maintained through mating of mice that are homozygous for the floxed Por allele and homozygous for the Alb-cre transgene.