IGF1R and neoplasm: To confirm whether IGF-1R could serve as a marker for BCSCs, BC0145 or BC0244 xenograft tumor cells were sorted into IGF-1R+/IGF-1R- (BC0145) or IGF-1Rhi/IGF-1Rlo cells (BC0244), respectively (the purity of FACS are shown in Figure S3D in Additional file 1), and tested for tumorigenicity in vitro and in vivo.