Furthermore, in addition to CXCL12-induced chemotaxis, we also showed that DLL4 increased CLL cell migration toward CXCL13, another chemokine known to play a role on CLL pathogenesis [20], and similarly to CXCL12, OMP-52M51 blocked this induction in NOTCH1-mutated CLL (n = 6; Fig. 5d). Here, DLL4 is linked to B-cell chronic lymphocytic leukemia.