ELAVL1 and breast cancer: To determine whether the expression of HuR, an RNA-binding post-transcriptional regulator, is essential for breast cancer bone metastasis, we used an MDA-MB-231 basal-like/triple-negative human breast cancer cell line that has exhibited well-characterized bone tropism in animal models35, 36 and established luciferase-transfected HuR-knockdown (shHuR) cells and control (shNC) cells with corresponding non-specific scrambled shRNA (Supplementary Fig. 1a).