FRAX597 is a potent group I PAK (p21-activated kinase) inhibitor (IC50 values are 8, 13 and 19 nM for PAK1, 2 and 3, respectively). Displays significant inhibition of YES1, RET, CSF1R and TEK at 100 nM, but is inactive against group II PAK isoforms (IC50 >10 μM for PAK4). FRAX597 inhibits the proliferation of NF2-deficient schwannoma cells in culture and displays potent anti-tumor activity in vivo. MW: 558.1. Purity ≥98% by HPLC