A 1089-bp DNA fragment between nucleotides 25,289,972-25,291,060 on Chromosome 2 (Genome Build 38) containing the entire protein coding sequence has been replaced by the ZEN-UB1 cassette, which contains the E. coli galactosidase gene (lacZ) and a loxP-flanked sequence comprising the promoter of the human ubiquitin C gene driving expression of neomycin phosphotransferase.