ESR1 and neoplasm: Over-expression of HOTAIR is correlated with poor tumor prognosis, The expression of HOTAIR is regulated by multiple factors at the transcriptional and post-transcriptional levels, including estrogen receptors and estrogen receptor coregulators such as histone methylases MLL1 and MLL3 and CBP/p300 binding to the promoter of HOTAIR and regulating HOTAIR expression (18) and Pumilio homolog 1 regulating HOTAIR expression via a post-transcriptional mechanism (19).