Pooled Human Liver S9 Fractions provide a fully characterized, relevant, reliable and reproducible in vitro tool. S9 Fractions from pools of 50 Donors provides an economic solution to derive an accurate population representation that may be used to describe the metabolic profile of a drug or drug candidate in high-throughput assays as well as the following other uses: Conduct studies of metabolic stability (% of original drug remaining over time) Identify which cytochrome P450 (CYP) enzymes oxidize a drug candidate and which UDP-glucuronosyltransferase (UGT) enzymes are responsible for glucuronidation Identify, quantify and characterize drug metabolites Describe a drug's metabolic pathways Identify inhibition of cytochrome P450 (CYP) enzymes