In addition, we demonstrate that terfenadine interacts directly with calcium/calmodulin dependent protein kinase II delta (CAMK2D) and inhibits the subsequent ectopic activation of the CAMK2/cAMP responsive element binding protein 1 (CREB1) pathway in an ABCB1-mediated MDR ovarian cancer line, A2780-ADR. The gene discussed is CAMK2D; the disease is ovarian cancer.