Aromatase (CYP19A, EC 184.108.40.206) is a member of the cytochrome P450 monooxidase (CYP) family of microsomal xenobiotic metabolism enzymes. Aromatase plays a critical role in steroidogenesis, catalyzing the conversion of androgenic hormones into estrogens. The enzyme is expressed in high levels in reproductive tissues, placenta, brain and adipose tissue and is responsible for mammalian sexual dimorphism and development of secondary sexual characteristics. Inhibitors of aromatase are used to treat estrogen-dependent breast cancer, as estrogens promote the expression of peptide growth factors responsible for tumorigenesis. Aromatase activity and expression can be affected by many organic environmental pollutants such as pesticides and plasticizers. Such compounds, known as endocrine disruptors, are suspected of causing precocious puberty, obesity, infertility and various cancers. The PromoKine Aromatase Inhibitor Screening Kit enables rapid screening of drugs and other small molecules for compound-Aromatase interaction in a reliable, high-throughput fluorescencebased assay. The assay utilizes a fluorogenic substrate that is converted into a highly fluorescent metabolite detected in the visible range (Ex/Em = 488/527 nm), ensuring a high signal-tobackground ratio with little interference by autofluorescence. The kit contains a complete set of reagents sufficient for performing 100 reactions in a 96-well plate format.