Actin microfilaments are a key component of the cytoskeletal network and play an important role in a number of cellular activities. Thus, the ability to visualize F-actin in living cells is crucial to the success of a wide variety of scientific investigations and experiments. Accordingly, a number of markers have been developed for live cell targeting of the actin cytoskeleton. One of the most recent additions to the researcher's arsenal of tools for this purpose is a peptide 17 amino acids long derived from yeast Abp140p called Lifeact. Studies indicate that the unique properties of Lifeact, including its small size and low binding affinity for F-actin, enable chimeric markers constructed with it to be used with live cells without impacting actin-dependent processes. In the digital video sequences presented in this section, F-actin is visualized with a mEmerald-Lifeact fusion and H2B is fluorescently labeled with mApple.