Retraction: Sinomenine Sensitizes Multidrug-Resistant Colon Cancer Cells (Caco-2) to Doxorubicin by Downregulation of MDR-1 Expression

• Zhen Liu, 
• Zhi-Jun Duan, 
• Jiu-Yang Chang, 
• Zhi-feng Zhang, 
• Rui Chu, 
• Yu-Ling Li, 
• Ke-Hang Dai, 
• Guang-quan Mo, 
• Qing-Yong Chang, 
• and the PLOS ONE Editors