He is a Member in the Immunology Program of the Sloan Kettering Institute and the Division of Infectious Diseases at Memorial Sloan Kettering, where he is an incumbent of the Alfred Sloan Chair. He is also Professor of Medicine, Immunology-Microbial Pathogenesis, and Molecular Biology at Weill Cornell Medical College. His laboratory has longstanding interests in the molecular pathogenesis of M. tuberculosis infection, focusing on the role of the cell envelope in pathogenesis, the role of the intramembrane protease Rip1 in Mtb virulence, and mechanisms of transcriptional regulation. He is also a strong proponent of mycobacteria as a fertile model system to understand prokaryotic biology, specifically in understanding microbial DNA damage responses. These fundamental insights have wide implications for understanding mycobacterial infections and antibiotic resistance.