GIFT4-CLL cells are distinguished from our prior GIFT4-B cells that secrete GM-CSF and CCL3 [11] and different from CD40/OX40-ligated CLL cells that produce IFN-γ [28], or CpG/IL-21 treated CLL cells that do not produce IL-2, ICAM-1, IL-6 and FGFB but secrete granzyme B [31]. Here, CSF2 is linked to B-cell chronic lymphocytic leukemia.