A reversibly photoswitchable GFP-like protein with fluorescence excitation decoupled from switching. by Brakemann, T, Stiel, A, Weber, G, Andresen, M, Testa, I, Grotjohann, T, Leutenegger, M, Plessmann, U, Urlaub, H, Eggeling, C, Wahl, M, Hell, S, Jakobs, S