ESR1 and breast cancer: Altogether, this thus indicates a positive impact of LXRs for protection against the development of breast cancer (Figure 4), even though 27-hydroxycholesterol, which is a LXR-ligand, acts as ERα ligand SERM [108] in breast cancer, cannot exclude a negative role of LXRs when 27-hydroxycholesterol increases, which has never been described so far.