In vitro activity: In A20 cells, PF-431396 blocks anti-Ig- and clustering LFA-1-induced tyrosine phosphorylation of Pyk2 and FAK, and further blocks B cell spreading. PF-431396 consistently inhibits the increase in protein tyrosine phosphorylation (PY) induced by the absence of added calcium and induced by W-7 in the presence of calcium.

Kinase Assay: PF-431396 is dual focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (PYK2) inhibitor (IC50 values are 2 and 11 nM respectively), PF-431396 has a Kd value of 445 nM for BRD4. IC50 value: 2 nM (FAK); 11 nM (PYK2); 445 nM (KD for BRD4) [1] [2] Target: FAK; PYK2; BRD4 in vitro: PF-431396 is a potent and highly selective pyrimidine-based inhibitor of both Pyk2 and FAK, Consistent with the idea that the tyrosine phosphorylation of Pyk2 and FAK involves an initial autophosphorylation or transphosphorylation step, treating A20 cells with PF-431396 blocked anti-Ig-induced tyrosine phosphorylation of Pyk2 and FAK when the cells were stimulated in suspension when they were stimulated on ECM. Nanomolar affinities were also determined for PF-431396 (Kd = 445 ± 42 nM) and for the PIM inhibitor (Kd = 565 ± 63 nM).