EGR1, CAV1, TAGLN and BCL11b are estrogen-responsive genes described as tumour suppressors in breast cancer [42]–[45], whereas the upregulated genes are estrogen-responsive genes described as breast cancer oncogenes (RET, BCAS1, TFF3) [46]–[48] or known to stimulate breast cancer metastasis and progression (CXCR4, ADM) [49], [50]. The gene discussed is CXCR4; the disease is breast cancer.