MPEP hydrochloride is an effective and highly specific non-competitive antagonist at the mGlu5 receptor subtype (IC50: 36 nM).

Biochemical kinase assays: Solubilized membranes from 3T3 Flk-1 cells are added to polystyrene ELISA plates that had been precoated with a monoclonal antibody that recognizes Flk-1. After an overnight incubation with lysate at 4 ℃, serial dilutions of SU5416 are added to the immunolocalized receptor. To induce autophosphorylation of the receptor, various concentrations of ATP are added to the ELISA plate wells containing serially diluted solutions of SU5416. The autophosphorylation is allowed to proceed for 60 min at room temperature and then stopped with EDTA. The amount of phosphotyrosine present on the Flk-1 receptors in the individual wells is determined by incubating the immunolocalized receptor with a biotinylated monoclonal antibody directed against phosphotyrosine. After removal of the unbound anti-phosphotyrosine antibody, avidin-conjugated horseradish pero-idase H is added to the wells. A stabilized form of 3,3 9,5,5 9-tetramethyl benzidine dihydrochloride and Water2 is added to the wells. The color readout of the assay is allowed to develop for 30 min, and the reaction is stopped with H2SO4.