Actin is an essential protein in the skeleton of a cell (cytoskeleton). It forms a dense network of fine filaments in the cell. Here, the researchers used a technique called stochastic optical reconstruction microscopy (STORM) to visualize the actin network in a cell in three dimensions. Actin strands were labeled with a dye called Alexa Fluor 647-phalloidin. This image appears in a study published by Nature Methods, which reports how researchers use STORM to visualize the cytoskeleton.