CXCL8 and leukemia: ATRA strongly enhanced the release of angiogenic mediators including CXCL8 by the endothelial cells; this may in vivo either result in (i) direct effects on autocrine cell signaling, (ii) inhibition of effects that ECs have on pericytes surrounding blood vessels or other stromal cells in the bone marrow, or (iii) it may potentially have an indirect paracrine effect on leukemia cells in vivo.