Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine CIRMMP 1 article published in JoVE Chemistry Monitoring Protein-Ligand Interactions in Human Cells by Real-Time Quantitative In-Cell NMR using a High Cell Density Bioreactor Letizia Barbieri1,2, Enrico Luchinat1,3 1Magnetic Resonance Center − CERM, University of Florence, 2Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine − CIRMMP, 3Neurofarba Department, University of Florence This protocol describes the setup of an NMR bioreactor to keep encapsulated human cells viable for up to 72 h, followed by time-resolved in-cell NMR data acquisition and analysis. The methodology is applied to monitor intracellular protein-ligand interactions in real time.