In ERO1 knock-down NALM6 cells (NALM6-shERO1), pevonedistat induced ERK1/2 phosphorylation was augmented compared to controls (NALM6-Luc) (Figure 2D), suggesting that UPR/CHOP/ERO1-induced Ca2+ release from the ER is likely only a minor contributor to p-ERK1/2 activation in pevonedistat-treated ALL cells. Here, MAPK3 is linked to acute lymphoblastic leukemia.