Consistent with the inverse correlation of HYAL1 and estrogen, MCF-7 and BT-474 cells showed reduced basal levels of HYAL1 protein when compared to ERα-negative breast cancer MDA-MB-231 and ovarian epithelial cancer TOV21G cells, which are both strongly positive for HYAL1 (Supplementary Figure S2). Here, ERAL1 is linked to breast cancer.