Chemicon's membrane preparations are crude membrane preparations made from our proprietary stable recombinant cell lines to ensure high-level of GPCR surface expression; thus, they are ideal HTS tools for screening of antagonists of FPR1 and its ligands. The membrane preparations exhibit a Kd of 0.39 nM for [125I]-WKYMVm. With 5 μg/well FPR1 Membrane Prep and 0.5 nM [125I]-WKYMVm, a greater than 20-fold signal-to-background is obtained; with 1.25 and 2.5 μg/well FPR1 Membrane Prep, greater than 9- and 15-fold signal-to-background ratios are obtained, respectively.