LTKB is a project at the FDA’s National Center for Toxicological Research to study drug-induced liver injury (DILI). Liver toxicity is the most common cause for the discontinuation of clinical trials on a drug, as well as the most common reason for an approved drug’s withdrawal from the marketplace. Because of this, DILI has been identified by the FDA’s Critical Path Initiatives as a key area of focus in a concerted effort to broaden the agency’s knowledge for better evaluation tools and safety biomarkers.