Highly selective ERK5/BMK1 inhibitor (KD values are 80, 190, 600 and 890 nM for BMK1, DCAMKL2, PLK4 and TNK1 respectively). Displays selectivity over 402 diverse kinases. Blocks growth factor-induced activation of cellular BMK1 and reduces BMK1 activity in in vitro kinase assays. Also reduces BMK1-dependent transactivating activity of MEF2C. Inhibits proliferation in a variety of cancer cell lines; blocks tumor cell proliferation and tumor-associated angiogenesis.