PLK4 and diabetic retinopathy: In high glucose-treated human retinal capillary endothelial cells miR-126 was shown to reduce experimental diabetic retinopathy and suppress endothelial cell proliferation by targeting polo-like kinase 4 (PLK4), which is a serine/threonine kinase playing a crucial role in cell cycle regulation, whose overexpression can lead to aberrant proliferation and apoptosis of endothelial cells [45].