PTGS2 and breast cancer: Animal and cellular experiments have shown that quercetin and kaempferol could downregulate AKT1, PTGS2, and VEGFA expressions [54–77] and upregulate TP53 expression [62, 71, 78–85] in various malignancies including breast cancer, prostate cancer, and non-small-cell lung cancer, which were the top 3 malignancies most likely to develop bone metastases [4–6].