NR0B1 and cancer: Beginning with metabolic enzyme targeting using folate and methotrexate, to targeting of DNA polymerase and topoisomerase (tamoxifen), to selective hormonal targeting of estrogens/androgens via their nuclear hormone receptors, to the more recent advancement of targeting human growth factor receptor kinases and their effectors, the gradual improvements in our understanding of cancer biology have led to new and numerous therapeutics.