A GFP reporter gene was inserted in-frame with the 5' end of the gene's coding sequence. The upstream conserved non-coding sequence 0 (CNS0 (Rr122); a STAT5-binding enhancer located at chrX:7,570,6747,571,274 (GRCm38) within intron 1 of Ppp1r3f) was flanked upstream by a loxP site and downstream by an FRT site flanked neomycin resistance gene cassette and a second loxP site. Flp-mediated recombination removed the neo cassette. Cre-mediated recombination removed CNS0. (J:305560)