A study by Roberg-Larsen et al. found an increased level of 27OHC in exosomes from the MCF-7 (ER+) breast cancer cell line compared to exosomes derived from an estrogen receptor (ER−) breast cancer cell line (MDA-MB-231) and other control exosomes (from a non-cancerous cell line (HEK293) and human plasma) [55]. This evidence concerns the gene ESR1 and breast cancer.