To confirm the endothelial regulation of Tie2 detected in the retina and further analyze the role of the Ang2–Tie2 axis upon loss of NDPK-B and hyperglycemia, we cultured macrovascular human umbilical vein endothelial cells (HUVECs), in which the efficient siRNA-mediated knockdown of NDPK-B was already established (Figure 2A, [10]), in medium containing normal (5 mM) or high glucose (30 mM, HG) for 24 h. Here, TEK is linked to Hyperglycemia.