Notch inhibition, in concert with VEGF stimulation, promotes lymphatic vessel sprouting. Notch signaling regulates quiescence of the lymphatic vasculature. On exposure to lymphangiogenic stimuli including VEGF and VEGF-C, Dll4 levels are elevated in lymphatic endothelial tip cells (green), presumably activating Notch signaling in neighboring lymphatic endothelial stalk cells and thereby preventing their sprouting. Notch pathway inhibition promotes lymphatic vascular sprouting induced by VEGF.