Bruton’s tyrosine kinase (BTK) is a cytoplasmic protein found in all hematopoietic cell lineages except for T cells. BTK mediates signaling downstream of a number of receptors.
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BTK occupancy assay

Primary AML cells and U937 were treated with increasing concentrations of ibrutinib (0.3-1000 nM) for 1 hour. Cells were then washed in phosphate-buffered saline and stored at −80°C until a BTK occupancy assay was performed as described.
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First we established the level of occupancy of the BTK active site by ibrutinib in AML cells. To do this, we treated primary AML sample #22 and AML cell line U937 with increasing concentrations of ibrutinib (3-1000 nM) for 1 hour.
http://www.bloodjournal.org/content/123/8/1229?sso-checked=t...