Targeting CSCs is a promising strategy to eradicate cancers and overcome drug resistant.8 Side population (SP) cells within tumors are a subset of cancer cells with stem-like properties that can be identified by flow cytometry analysis because of their highly expressed ABC transporters.21 It is reported that having low ROS levels is crucial to maintain the sub-population of CSCs in cancers.22 Thus, we envisioned that our synthetic compound LBL21 would effectively eliminate SP cells via modulating ROS accumulation. This evidence concerns the gene ABCG2 and cancer.