(A) SDS-PAGE of the mCherry-CBP fusion construct loaded on a 12% gel: ladder (lane 1), unmodified mCherry (lane 2), mCherry-Cbox (lane 3), mCherry-Tri-CBP (lane 4) (B) SDS-PAGE of the GFP-Wbox fusion constructs loaded on a 12% gel: ladder (lane 1), GFP-Wbox (lane 2), unmodified GFP (lane 3). (C) The molecular weights of mCherry, mCherry-Cbox, mCherry-TriCBP, GFP, and GFP-Wbox constructs as determined by mass spectrometry (supporting information, Figure S1).