FlAsH-EDT2 is a protein labeling reagent. FlAsH-EDT2 also is a membrane-permeant fluorogenic biarsenicals. FlAsH-EDT2 binds to CCXXCC motifs and non-specifically to endogenous cysteine-rich proteins. FlAsH-EDT2 can be useful only for labeling those recombinant proteins that express at a very high level[1][2].