Understanding the mechanisms involved in cell construction requires a method for visualizing the activity of the various factors responsible. This is particularly useful for observing signal transduction which involves the coordination and intracellular transport of signaling factors. Consequently, to understand signal transduction, it is important to visualize diffusion and transport of signaling factor. While fluorescent recovery after photobleaching (FRAP) is usually used to visualize intracellular transport and lateral diffusion of the proteins on cell membrane, we chose a new method involving the use of the photochromic protein, "Dronpa", to visualize diffusion and measure cell activity. The method enabled us to select and visualize cellular components at a variety of spatial scales using a fluorescent probe. By transfection of Bovine arterial endothelial cells (BAECs) to express Dronpa, we were able to visualize the fluorescent diffusion of Dronpa in the cytoplasm. Interestingly, cytoplasm diffusion is not isotropic.