Lin28B is known as an inhibitor of the let-7 miRNA family and has been reported that repression of let-7 miRNAs augments breast cancer stem-like cell expansion.15, 30 In conjunction with this, let-7 target genes such as HMGA2 and AURKA induce the self-renewal potential of hematopoietic stem cells and glioma-initiating cells, respectively.31, 32 The miRNA PCR array results showed that the let-7 family members were downregulated in shM1 cells when compared with expression in control cells (Supplementary Table S3). Here, LIN28B is linked to breast cancer.