TOX2 and B-cell chronic lymphocytic leukemia: TOX2 is specifically expressed in the tumor-specific B cell subpopulation (B7) in CLL donor (44/369), but it is almost not expressed in the other two B cell subpopulations (5/522 and 0/535) in CLL donor, nor is it expressed in B cell subpopulation in the healthy donor (3/469).