Don't use eGFP.

PLoS ONE has a great paper on eGFP overexpression inhibition of polyubiquitination both through Lysines 63 & 48.
Overexpression of this super popular fluorescent reporter protein effects polyubiquitination and the subsequent digestion via the proteasome to a degree that it signifantly stabilizes p53 and increases p53 downstream signalling.
Crazy. I wonder how it inhibits ubiquitination.