We are developing a strategy to get proteins directly into cells, which would be very useful for gene therapy and other kinds of new medical applications. For this strategy, we attach molecules called cell-penetrating peptides to proteins, and the peptides help the protein enter into cells. Once the complex successfully enters the cell, the peptides fall off of the protein and the protein can perform its function. Here, to test the ability to get proteins into cells we attached cell-penetrating peptides to a fluorescently tagged protein. We wanted to check whether the protein actually entered inside the cells, and this microscopy experiment showed that it did.