Schematic overview of gene transfer methods for live cell imaging studies. Depicted are methods for gene delivery and expression of fluorophore tagged proteins, (A) Transient and stable expressions of genes using viral or synthetic vectors, microinjection and lipofection. The later is the most frequently used method for gene transfer. Bacterial vectors of Listeria and Salmonella sp although hurdled by low transfection efficiency have been used for special cell lines. (B) Recombinant plasmid expressing fusion protein (target protein and fluorophore) under a common promoter (P) in host cells. Incorporation of a selection marker (SM) in the plasmid provides opportunity for controlled expression of the cloned genes. Upon excitation with specific wavelength, the fluorescence images are captured using appropriate filters. This provides the information on localization and probable interactions of the target protein with different cell organelles and/or other biomolecules. Cell organelles or structures can be stained using synthetic dyes such as Oil Red O for intracellular staining of lipid droplets. P: promoter, TP: target protein encoding gene and protein, FP: fluorescent protein encoding gene and protein, LD: lipid droplet stained with Oil Red O.