NFKB1 and breast carcinoma: Butein, another natural polyphenol derived from the stembark of cashews and the heartwood of Dalbergia odorifera, down-regulates the expression of CXCR4 (a Gi protein-coupled receptor for the ligand CXCL12) in HER2-overexpressing breast cancer cells via transcriptional regulation as indicated by inhibition of NF-κB activation and down-regulation of mRNA expression [45].