An FRT cassette separates the αTub84B promoter from sequence encoding wts that has been mutated to carry a S920A amino acid substitution (mutation of the residue that is the likely target of auto-phosphorylation to a non-phosphorylatable residue), and which is tagged at the N-terminal end with Citrine and at the C-terminal end with mTFP1. mTFP1 and Citrine can act as a fluorescence resonance energy transfer (FRET) pair (donor and acceptor respectively), and changes in the quenching ratio (acceptor channel emissions/donor channel emissions) can be used to monitor conformational changes in the mutant wts protein in vivo.