The authors repeated experiments and found that the results shown in figure 2 were not reproducible. Reference: Shuang-li Zhang, Bao-lin Li, Wei Li, Ming Lu, Lin-ying Ni, Hui-li Ma, Qing-gang Meng. The Effects of Ludartin on Cell Proliferation, Cell Migration, Cell Cycle Arrest and Apoptosis Are Associated with Upregulation of p21WAF1 in Saos-2 Osteosarcoma Cells In Vitro. Med Sci Monit 2018; 24: LBR4926-4933. 10.12659/MSM.909193.