Fluorescence Polarization Competition Assay: A fluorescence polarization competition immunoassay was used to measure compound inhibition of CSF-1R phosphorylation of tyrosine on a synthetic CSF-1R555-568 peptide (SYEGNSYTFIDPTQ). The assay was performed in black 96-well microplates (Cat #42-000-0117, Molecular Devices, Sunnyvale, Calif.). To each well, 5 μL of compound (in 4% DMSO) were mixed with 2 μL of 3.5 nM CSF-1R, 25 mM MgCl2 in assay buffer (100 mM HEPES (hydroxyethylpiperazineethylsodiumsulfonate), pH 7.5, 1 mM DTT (dithiothreitol), 0.01% Tween-20), and 2 μL of 1540 μM peptide in assay buffer. The kinase reaction was initiated by adding 1 μL of 10 mM ATP in assay buffer. The final concentrations in the 10 uL reaction mixture were 100 mM HEPES, pH 7.5, 1 mM DTT, 0.01% Tween-20, 2% DMSO, 308 μM SYEGNSYTFIDPTQ, 1 mM ATP, 5 mM MgCl2, and 0.7 nM CSF-1R.
Inhibition of c-fms (unknown origin) assessed as inhibition of CSF-1R phosphorylation of tyrosine on synthetic CSF-1R (555 to 568) peptide using 1 nM enzyme incubated for 80 mins by fluorescence polarization competition immunoassay
Inhibition of c-fms in mouse bone marrow macrophages assessed as reduction in recombinant mouse CSF-1-driven cell proliferation by measuring bromodeoxyuridine incorporation incubated for 30 hrs by ELISA