Considering that CAMK2 activation can phosphorylate and activate CREB1 (63) and that phosphorylated CREB1 binds to the CRE binding site in the ABCB1 promoter and promotes ABCB1 expression (64), CAMK2 activation will induce ABCB1 expression in cancer cells, resulting in MDR. Here, CREB1 is linked to cancer.