In estrogen receptor (ER) positive breast cancer, lncRNA BDNF-AS, driven by a MEF2A regulated enhancer, induces endocrine resistance of breast cancer by activating the RNH1 (ribonuclease inhibitor 1)/TRIM21/mTOR (mechanistic target of rapamycin) cascade 57. The gene discussed is RNH1; the disease is breast carcinoma.