VDR and acute myeloid leukemia: We have previously reported that the antileukemic synergy between VDDs and Nrf2 activators is associated with a mutual upregulation of VDR and Nrf2 signaling [22,28] and that Nrf2 may function as an upstream regulator of VDR, RXRα, and AP-1 protein levels in AML cells [22].