In breast cancer, one study found SATB1 mRNA expression levels to be higher in ER negative compared to ER positive tumours[20] and in another study, high SATB1 mRNA expression was found to correlate with an improved prognosis in ER positive but not in ER negative tumours, although this did not remain significant in multivariable analysis[21]. This evidence concerns the gene ESR1 and breast cancer.