Retraction Note to: Characterization of cancer stem-like cells in the side population cells of human gastric cancer cell line MKN-45

Objective Side population (SP) cells may play a crucial role in tumorigenesis and the recurrence of cancer. Many kinds of cell lines and tissues have demonstrated the presence of SP cells, including several gastric cancer cell lines. This study is aimed to identify the cancer stem-like cells in the SP of gastric cancer cell line MKN-45.