In this study, we have demonstrated several important points: 1) 25-OCH3-PPD suppresses the growth of breast cancer in vivo; 2) 25-OCH3-PPD inhibits MDM2 expression at both transcriptional and post-translational levels; 3) the inhibition of MDM2 by 25-OCH3-PPD is essential for its anti-tumor activities; and 4) 25-OCH3-PPD inhibits breast cancer cell migration in vitro and metastasis in vivo. Here, MDM2 is linked to neoplasm.