CXCR2 and leukemia: Furthermore, HSC-prog cells showed more interactions with other cells through known ligand–receptor pairs, such as leukaemia-associated ligands CXCL2, CXCL3, and FLT3, signalling to the receptors CXCR1 and CXCR2 expressed by CD14-mono and NK cells [55, 56] (Fig. 6e).