Fig. 4.

Irradiation-induced retraction and death of endothelial cells. Ionizing radiation exposure is able to decrease PECAM-1 expression, redistribute VE-cadherin, and produce actin stress fibers leading to endothelial retraction. Depending on the radiation dose, radiation quality, and inherent radiation sensitivity, ionizing radiation can activate the caspase pathway by ceramide formation and persistent p53 signaling, causing endothelial cell death. As a consequence of endothelial retraction and cell death, the physiological endothelial barrier is compromised