A loxP site flanked neomycin resistance gene cassette replaced the 810 bp encompassing the DNaseI hypersensitivity site 5 (HS5) in conserved non-coding sequence 2 (CNS-2) downstream of Il4, between it and Kif3a. Cre-mediated recombination removed the neo cassette. RT-PCR confirmed the reduction of Il4 and Il13 transcript expression in Th2 polarized CD4+ T cells. (J:181313)