BTK and acute myeloid leukemia: Compared to the sensitive B-lymphoblastic leukemia cell line, Daudi, the AML cell lines TEX, OCI-AML2, HL60, and U937 were relatively insensitive to ibrutinib, with IC50s ranging from 4- to 30-fold higher than Daudi cells in the Alamar Blue Assay, which measures cell proliferation and viability (Figure 1D) and much higher than the 1 μM concentration required to reduce levels of phospho-BTK.