Model mechanisms by which CIP2A regulates PP2A and BCR-ABL1 signaling proteins. Possible mechanism of PP2A inhibition in CML. In most patients, PP2A is suppressed by SET, which is driven by BCR-ABL1 via JAK2. In patients destined to progress into BC, PP2A is inhibited by CIP2A both directly as well as through BCR-ABL.¹