Fig. (1). LANCE Ultra TR-FRET technology for kinase assays In these kinase assays, the binding of a Eu-labeled anti-phospho- Tyr antibody (Eu-Ab) to the phosphorylated ULight-labeled substrate brings donor and acceptor molecules into close proximity. After irradiation of the kinase reaction at 320 or 340 nm, the energy from the Eu donor is transferred to the ULight acceptor dye which, in turn, generates light at 665 nm. The intensity of the light emission is proportional to the level of ULight-substrate phosphorylation.