PON2 and chronic myelogenous leukemia, BCR-ABL1 positive: In research focused on clarifying the potential contribution of PON2 to imatinib resistance in CML patients, data reported in a study by Witte et al. demonstrated that enzyme upregulation in the Bcr-Abl-positive K562 CML cell line protected the cells from injury and death induced by apoptosis associated with imatinib, acting as a Bcr-Abl tyrosine-kinase inhibitor.