ESR1 and breast neoplasm: Specific estrogen-regulated lncRNAs such as long non-coding RNA 152 (LncRNA152) and long non-coding RNA 67 (LncRNA67) show significantly higher relative expression levels in ER-positive (ER+) breast tumors in comparison to non-cancerous breast tissue, and upon estrogen treatment, can regulate cell proliferation and mitogenic division in ER+ cell lines [35].