B3GALT4 and breast cancer: In the present study, we explored the effect of GM1 on the biological function of secretions by treating human normal mammary epithelial MCF-10A cells and breast cancer MCF-7 cells with conditioned medium (CM) from B3GALT4-overexpressed (termed as B3GALT4-CM) and -silenced (shB3GALT4-CM) MDA-MB-231 cells (Figure 2A).