LFM-A13 (244240-24-2) is a selective inhibitor of Bruton’s tyrosine kinase (BTK) – IC50‘s = 2.5 μM (recombinant BTK) and 17.2 μM (human BTK).1,2 It has also been shown to inhibit Polo-like kinase (PLK) – IC50 = 61 μM for human PLK3.3 LFM-A13 displayed no activity (concentrations up to 278 μM) at JAK1, JAK3, HCK, EGFRK and IRK2 or CDK1-3, CHK1, IKK, MAPK1, SAPK2a and ten other tyrosine kinases.3