PD318088 is an allosteric and non-ATP competitive MEK1/2 inhibitor.

PD318088 is an analog of PD184352, which means it might have important anti-proliferative activity against cancer cells, although no functional study of PD318088 is currently available. PD318088 binds simultaneously with ATP in a region of the MEK1 active site that is adjacent to the ATP-binding site. Formation of the ternary complexes with PD318088 and MgATP results in moderate increases (to 140 nM) for the Kd monomer-dimer for both MEK1 and MEK2. PD318088 and MgATP together increase the dimerization disassociation constant for MEK1 and MEK2 slightly from ~75 nM to ~140 nM [1].

PD318088 is a biarylamine compound co-crystallized with MEK. G8935 occupies the unique pocket adjacent to ATP binding site and is uperimposed with PD318088 .PD318088 averts to use the pocket formed by Ile216, Phe209, Arg189, and Asp190. [2]

References:
1. Ohren JF1, Chen H, Pavlovsky A et al.  Structures of human MAP kinase kinase 1 (MEK1) and MEK2 describe novel noncompetitive kinase inhibition. Nat Struct Mol Biol. 2004 Dec;11(12):1192-7. Epub 2004 Nov 14.
2. Han S, Zhou V, Pan S et al.  Identification of coumarin derivatives as a novel class of allosteric MEK1 inhibitors. Bioorg Med Chem Lett. 2005 Dec 15;15(24):5467-73. Epub 2005 Sep 30.