STIM1 and B-cell chronic lymphocytic leukemia: To address this issue (Fig. 5a), B-CLL cells from 28 patients (11 CE+ and 17 CE-) were tested by FACS for STIM1 expression using STIM1 mAb following permeabilization of the cells (total-STIM1 expression determination) or not (STIM1PM quantification).