THBS4 and B-cell chronic lymphocytic leukemia: Taken together with the killing defect of SMAPs released by TSP-4 deficient CTLs, the fact that SMAPs released by CTLs exposed to the culture supernatants of CLL cells have an impaired killing ability further highlights the importance of TSP-4 in SMAP function, although further work is required to determine whether SMAPs play an important role in killing of CLL cells.