The fluorescent protein Emerald and its monomeric form (mEmerald) were produced via the directed mutation of EGFP. Named for the gemstone with similar coloring, the green fluorescent proteins exhibit more brightness and photostability than their predecessor. The fox lung cells appearing in the digital video sequences presented in this section are shown expressing a mEmerald fusion tag with H2B, highlighting cell nuclei. The cells were additionally labeled with mCherry fused to farnesyl.