ABCG2 and cancer: Chalcone derivatives act on various targets, such as aromatase, ATP binding cassette subfamily G member 2 (ABCG2), breast cancer resistant protein (BCRP), activated nuclear B cell growth factor (NF-ĸB), vascular endothelial growth factor (VEGF), and tyrosine kinase receptors (epidermal growth factor receptor (EGFR) and mesenchymal epithelial transition factor (MET), showing important activities in vitro and in vivo in susceptible and therapy-resistant cancers [161,162].