Since TLR4 could also be expressed by BC cells per se, to exclude the possible effect of carry-over of TLR4 ligand via the Mφ-conditioned medium, we compared levels of ERα protein in untreated BC cells (E0771, MCF-7) versus those incubated with medium conditioned by LPS (0.1 ng/mL)–stimulated Mφ, or those incubated with standard medium containing the same concentration of LPS. Here, TLR4 is linked to breast cancer.