INS and obesity due to melanocortin 4 receptor deficiency: In brief, our strategy was to a) solicit input from experts in the mechanisms of diabetes and obesity who participated in a 2011 NTP workshop, “Role of Environmental Chemicals in the Development of Diabetes and Obesity” (Thayer et al. 2012) to identify assay targets relevant to biological processes related to diabetes and obesity (e.g., insulin sensitivity in peripheral tissue, pancreatic islet and β cell function, adipocyte differentiation, and feeding behavior); and b) identify chemicals that perturb these targets or pathways.