Egner, A., Verrier, S., Goroshkov, A., Soling, H. and Hell, S. W.
4Pi-microscopy of the Golgi apparatus in live mammalian cells. Journal of Structural Biology 147: 70-76 (2004).

We report the applicability of 4Pi-microscopy to live mammalian cells. Controlled interference of the counterpropagating wavefronts is possible despite the slight variations in cellular refractive index. Superresolved 3D-fluorescence imaging is exemplified with the first representation of the Golgi apparatus in a live cell at ~100 nm resolution.