In CLL, the matrix glycoprotein Thrombospondin-1 (THBS1), a versatile player of the microenvironment, is capable of inducing caspase independent apoptosis of leukemic cells via CD47 ligation34–36, and increased THBS1 levels are associated with better survival of CLL patients13. Here, CD47 is linked to B-cell chronic lymphocytic leukemia.