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I have used membrane-targeted fluorophores for visualizing neuronal morphology 
off and on over the years. Some colleagues have warned me about their potential 
side affects, and although I have always been cautious of this I have not 
experienced this until just recently. I also have never seen a publication that 
describes these effects. 

In my setup I have been using a membrane-targeted form of citrine I made by 
adding the Ras CAAX prenylation site to the C-term of citrine. Unless it is 
expressed at very low concentrations it causes both obvious morphological 
defects, and leads to early cell death. I have used a similarly made version of 
Venus which has a very similar sequence, and not seen these effects, though in a 
slightly different experiment. 

Does anyone have more knowledge of what membrane-targeted fluorophores are 
best. I am considering using a palmitoylation sequence since I have it on hand, 
but am not sure if that will help. Not sure if it is the fluorophore, the linker or the 
lipid modification that leads to the problem, and am just generally curious what 
other people think.