AXL and B-cell chronic lymphocytic leukemia: Thus, to define the Axl activation status in the latter CLL patients, we immunoprecipitated total Axl from CLL B-cell lysates of relapsed/refractory, ibrutinib exposed patients (n=6; Table 1), followed by Western blot analysis was done using an anti-phospho-tyrosine antibody to detect total P-Axl levels.