WAS and chronic myelogenous leukemia, BCR-ABL1 positive: To our surprise, treatment of CML cell lines with imatinib did not show any sign of recovery of WASP, suggesting that the inhibition of WASP by BCR–ABL1 is either a kinase-independent event or may undergo a secondary layer of regulation that does not depend on the constant kinase activity of BCR–ABL1.