A series of 1-aryl-3, 4-dihydroisoquinoline inhibitors of JNK3 are described. Compounds 20 and 24 are the most potent inhibitors (pIC50 7.3 and 6.9, respectively in a radiometric filter binding assay), with 10-and 1000-fold selectivity over JNK2 and JNK1, respectively, and selectivity within the wider mitogen-activated protein kinase (MAPK) family against p38α and ERK2. X-ray crystallography of 16 reveals a highly unusual binding mode where an H- ...