The calculated Forster distance (R0= 5.7 nm) for the TagGFP-TagRFP pair is one of the largest among the values reported. At the same time, since TagGFP and TagRFP emission peaks are spaced by as much as 79 nm, the emission signal for these two proteins can be easily separated in any imaging system.Shifting the wavelengths toward the red part of the spectrum (comparing to traditional cyan and yellow FRET partners) reduces input of cellular autofluorescence [Shcherbo et al., 2009].