It is also of note that diverse chalcone derivatives have a real potency even in the therapy of drug resistance as they display promising in vitro and in vivo effects on both drug-susceptible and drug-resistant cancers while also being capable of acting on a variety of targets, such as aromatase, breast cancer resistance protein (BCRP), vascular endothelial growth factor (VEGF) and ATP binding cassette subfamily G member 2 (ABCG2) [16,17]. This evidence concerns the gene ABCG2 and cancer.