A system and associated method measures anomalous diffusion of biomolecules in cell membranes of intact cells and includes a laser that illuminates a cell membrane within an intact cell to express fluorescently tagged biomolecules. The laser photobleaches a region of interest and illuminates the region of interest over time. A detector detects the fluorescence recovery over time within the region of interest to yield fluorescence recovery after photobleaching (FRAP) data. A controller computes the mean square displacement (MSD) of diffusing biomolecules and a time-dependent diffusion coefficient D(t) from a plurality of time points of the FRAP data and determines the anomalous diffusion in the cell membrane.