The human DAO cell assay routinely employed a CHO-K1 clone, which was stably transfected with a mammalian expression plasmid containing the human DAO nucleotide encoding the full-length human DAO protein. This cell line was originally generated as described in . The human DAO CHO-K1 stable cell line was routinely cultured in Gibco Ham's F-12 Nutrient Mix (31765-027, ThermoFisher Scientific) containing 10% FBS (10082-147, ThermoFisher Scientific) and 500 µg/mL Geneticin™ Selective Antibiotic (10131-027, ThermoFisher Scientific).