BCAR4 was identified from functional screening for the genes responsible for tamoxifen resistance in breast cancer cells;13 notably, BCAR4-positive breast cancer demonstrated aggressive phenotypes and resistance to treatment.14–16 In its function as a lncRNA, BCAR4 promotes the metastasis of breast cancer by activating cell migration via a non-canonical Hedgehog/GLI2 signalling pathway. This evidence concerns the gene GLI2 and breast cancer.