New York University Medical Center 2 articles published in JoVE Biochemistry A Semi-Quantitative Drug Affinity Responsive Target Stability (DARTS) assay for studying Rapamycin/mTOR interaction Chen Zhang*1, Min Cui*1, Yazhou Cui1, Aubryanna Hettinghouse1, Chuan-ju Liu1,2 1Department of Orthopaedic Surgery, New York University Medical Center, 2Department of Cell Biology, New York University School of Medicine In this study, we enhanced the data analysis capabilities of the DARTS experiment by monitoring the changes in protein stability and estimating the affinity of protein-ligand interactions. The interactions can be plotted into two curves: a proteolytic curve and a dose-dependence curve. We have used mTOR-rapamycin interaction as an exemplary case. Bioengineering Establishment of a Surgically-induced Model in Mice to Investigate the Protective Role of Progranulin in Osteoarthritis Yunpeng Zhao1, Ben Liu1, Chuan-ju Liu2 1Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 2Department of Orthopaedic Surgery, New York University Medical Center We describe a protocol for the destabilization of the medial meniscus (DMM) model in mice, an effective tool for osteoarthritis (OA) research. In addition, we have demonstrated that deficiency of progranulincan exaggerate OA development and progression by using this model, indicating that progranulin plays a protective role in the pathogenesis of OA.