VCAM1 and leukemia: To investigate if the adhesion between leukemia cells and ECs induces EC UPR response and PERK activation, we blocked the ligands of ICAM-1 and VCAM-1 and found that PERK, eIF2a, and JAG1 activation was modestly attenuated by blocking LFA-1 but largely unaffected by blocking VLA-4 (Fig. S8A-B).