The transgene contains the following elements: an Igf2 silencer from upstream of Igf2, Igf2 promoter 3 (Rr146; from 162 bp upstream of TSS of exon 3/alternative exon 1 [chr7:142211218 GRCm39] to 74 bp of 5' UTR in exon 3), the luciferase reporter gene and SV40 poly(A) signal sequences. A number of independent lines were generated. (J:334634)