Rr27^tm3.1Pes

The ICR (2.4 kb BglII fragment with chromatin insulation, promoter silencing and imprinting (differential methylation) function) between the Igf2 and H19 genes was replaced with a loxP site flanked neomycin resistance gene cassette and a 2.4 kb sequence containing two copies of a mutated version of the chicken beta globin chromatin insulator ((mChbetaGI)2). The mutations deleted or disabled FP1 (VEZF1 binding site), FP3 (VEZF1), FP4 (USF binding site), and FP5 (VEZF1). The neo cassette was removed through subsequent cre-mediated recombination. (J:308568)