The current mechanisms proposed to explain how tumor cells gain access to the lymphatic vasculature and establish sentinel LN metastasis include: (i) the growth and remodeling of the lymphatic vasculature in the tumor microenvironment; (ii) the increased fluid drainage from tumor tissue, which provokes the passive transport of tumor cells; and (iii) the guidance of tumor cell migration towards lymphatic vessels by chemokines such as CCL21 and CXCL12, produced by activated LEC28, 38, 39. The gene discussed is CCL21; the disease is neoplasm.