AIT Bioscience 1 article published in JoVE Biochemistry Characterizing Cellular Proteins with In-cell Fast Photochemical Oxidation of Proteins Emily E. Chea1, Aimee Rinas2, Jessica A. Espino1, Lisa M. Jones1 1Department of Pharmaceutical Sciences, University of Maryland Baltimore, 2AIT Bioscience Here, we characterize protein structure and interaction sites in living cells using a protein footprinting technique termed in-cell fast photochemical oxidation of proteins (IC-FPOP).