HDAC9 and cancer: Chalcones are potential inhibitors of aromatase, P-glycoprotein (P-gp), histone deacetylase (HDAC), matrix metalloproteinase (MMP), NF-κB, tubulin, vascular endothelial growth factor, and vascular endothelial growth factor receptor 2 (VEGFR-2) kinase; thus, chalcones are endowed with broad-spectrum antiproliferative activity against drug-susceptible and drug-resistant cancers, even MDR cancers (Karthikeyan et al., 2015; Gao et al., 2020).