While most small fluorescent molecules such as FITC (fluorescein isothiocyanate) are strongly phototoxic when used in live cells, fluorescent proteins such as GFP are usually much less harmful when illuminated in living cells.
Aínda que as pequenas moléculas fluorescentes como a FITC (fluoresceína isotiocianato) son moi fototóxicas cando se usan nas células vivas, as proteínas fluorescentes como a GFP son xeralmente moito menos nocivas cando iluminan ás células vivas.