Peripheral blood samples were frozen at −80°C. All samples from each experiment were thawed and analyzed for dasatinib concentration at the same time. Once thawed, dasatinib concentrations were determined using an assay developed to monitor a structurally similar compound IM by LC/LC-MS/MS (27 (link)), with minor modifications. Using this assay, concentrations of dasatinib in whole blood can be determined with a lower limit of detection of 50pg/ml. PK parameters such as half-life (T½), peak concentration (Cmax), and area under the curve (AUCinf) were calculated using WinNonlin software (Pharsight, St. Louis, MO).