In this context, Yuh-Ying Yeh and co-workers have identified the tetraspanin, CD9, CD63, and CD37 as abundantly expressed markers in tumor exosomes of CLL patients by flow analysis and immunoblotting, in contrast to the modest expression of CD41, CD56, and CD3 [67]. This evidence concerns the gene CD63 and B-cell chronic lymphocytic leukemia.