[Photobleaching properties of GFP expressed in human lung cancer cells]

The characteristic properties of GFP make this protein a good candidate for use as a molecular reporter to monitor patterns of protein localization, gene expression, and intracellular protein trafficking in living cells. In this study, the dicistronic expression vector (pEGFP-C1) was used to be transfected into human lung cancer cell line (ASTC-a-1) and a positive clone which stably expressed GFP in high level was obtained. The results showed that the green fluorescent protein expressed in tumor cells was also photobleached under intense irradiation (-488 nm) and the degree of photobleaching varied with the intensity of the excitation. In order to analyze the effect of low temperature on the fluorescent sample, the photobleaching of tumor cell slice stored at -20 degrees C was observed additionally.