ESR1 and obesity due to melanocortin 4 receptor deficiency: On the other hand, in vitro treatment with recombinant heparanase enzyme prior to stimulation by SFA (mimicking overexpression of the enzyme in obesity-associated breast tumors [30]) resulted in a 4-fold increased ability of SFA-stimulated Mφ to upregulate ERα expression in E0771 and MCF7 cells (Supplementary Figure S4).