THBS1 and B-cell chronic lymphocytic leukemia: Also, despite the description of CD47 expression as an advantageous feature for neoplastic cells, CD47 ligation by monoclonal antibodies can induce apoptosis in many tumor cell lines, such as chronic lymphocytic leukemia cells (24), and binding of CD47 by TSP-1 has also been described to induce cell apoptosis (14).