ESR1 and cancer: In endocrine-resistant breast cancer models such as aromatase inhibitor-resistant MCF-7 cells, SREBP1 not only activates lipogenesis and the formation of hydroxy cholesterol, re-activating ERα and enhancing cancer cell survival, but it also drives the upregulation of Keratin-80 (KRT80) by binding to the enhancer region of the gene and activating its transcription [83].