A selective ERK5 inhibitor (IC50 = 0.162 μM in an enzyme assay); selective for ERK5 over a panel of more than 200 kinases at 10 μM; inhibits ERK5 phosphorylation (IC50 = 0.09 μM in HeLa cells); decreases AP-1 transcriptional activity (EC50 = 4.2 μM); inhibits human recombinant LRRK2[G2019S] (IC50 = 0.339 μM in an enzyme assay)