Celastrol (Fig. 2i) is an active triterpenoid isolated from Tripterygium wilfordii which reduces active levels of phospho BCR-ABL and total BCR-ABL in CML cells bearing wild-type BCR-ABL and in T315I mutant (BCR-ABL resistant to imatinib mesylate) cells. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.