Willig, K. I., Kellner, R. R., Medda, R., Hein, B., Jakobs, S. and Hell, S. W.
Nanoscale resolution in GFP-based microscopy. Nature Methods 3: 721-723 (2006).

We report attainment of subdiffraction resolution using stimulated emission depletion (STED) microscopy with GFP-labeled samples. The ∼70 nm lateral resolution attained in this study is demonstrated by imaging GFP-labeled viruses and the endoplasmic reticulum (ER) of a mammalian cell. Our results mark the advent of nanoscale biological microscopy with genetically encoded markers.