CCL21 and neoplasm: Our present results prompt for the first time that a closed loop/circular communication exists between CCL21/CCR7 and VEGF-C/VEGFR-3 axes, in a sense that not only VEGF-C promotes CCL21 secretion by LECs [21], but also that CCR7 activation stimulates VEGF-C synthesis by tumor cells and thus drives lymphangiogenesis.