Due to their interaction with the microfilament actin, members of the cross-linking and bundling protein family known as alpha-actinin are popular targets for fluorescently tagging the cytoskeletal actin network. In non-muscle cells, alpha-actinin proteins are usually sensitive to calcium, whereas in muscle cells the proteins typically exhibit insensitivity to calcium. In the digital video sequences presented in this section, alpha-actinin was targeted with mEmerald. The U2OS cells were also labeled with mCherry fused to farnesyl.