Figure 1. In breast cancer, PoEMs migrate towards the lymphatic endothelium. In this niche, they stimulate lymphangiogenesis by means of matrix remodeling resulting in the accessibility of growth factors. Moreover, Collagen I synthetized by PoEMs constitutes a scaffold for growing lymphatics. Directly and indirectly, matrix remodeling by PoEMs also fuels cancer cell lymphoinvasion.