PD176252 is a potent antagonist of neuromedin-B preferring ( BB 1 ) and gastrin-releasing peptide-preferring ( BB 2 ) receptor with K i s of 0.17 nM and 1 nM for human BB 1 and BB 2 receptors, and 0.66 nM, 16 nM for Rat BB 1 and BB 2 receptors, respectively; PD176252 is also an agonist of N-Formyl peptide receptor1/2 ( FPR1/FPR2 ), with EC 50 s of 0.31 and 0.66 μM in HL-60 cells.