An irreversible inhibitor of BMX (IC50 = 8 nM) and BTK (IC50 = 10.4 nM); inhibits the proliferation of Tel-BMX-transformed Ba/F3 prostate cancer cells (GI50 = 25 nM), as well as RV-1, DU-145, PC-3, and VCAP prostate cancer cell lines (GI50s = 2.54, 4.38, 5.37, and 2.46 µM, respectively).