The ability to observe the dynamic localization of a protein in living cells can provide critical insight to its mode of action and functional molecular interactions. To this purpose, green fluorescent protein (GFP) has served as a powerful tool to tag STAT proteins for microscopic visualization. Live cell imaging with STAT-GFP proteins has contributed to our understanding of signal transduction and the complexities of nuclear transport of STAT proteins. In this report we summarize recent approaches that use GFP-based techniques with live cell imaging to study the mechanisms of STAT nuclear import and export: photoactivation, fluorescence recovery after photobleaching (FRAP), and fluorescence loss in photobleaching (FLIP).
