TCS JNK 5a(JNK Inhibitor IX) is a selective inhibitor of JNK2 and JNK3 (pIC50 values are 6.7, 6.5, <5.0 and <4.8 for JNK3, JNK2, JNK1 and p38α respectively); displays no significant activity at a range of other protein kinases including EGFR, ErbB2, cdk2.