Representative western blots of phospho-Akt, total Akt, phospho-PTEN, total PTEN, phospho-p38MAPK, p65/RelA, phospho-ERK1/2, phospho-PDK-1, Bcl-2 and Bcl-XL in HUVECs transfected or not with siRNA PAI-1 24 hours after 20 Gy (A). Representative western blots of phospho and total Akt in HUVECs that stably overexpress PAI-1. Akt activation is reduced in human ECs that overexpress PAI-1 (B). Silencing efficiency determined by western blot in HUVECs transfected with siRNA PTEN or siRNA PDK-1 (C). Representative images of HUVECs knocked-down for PTEN, PDK-1, PAI-1, PTEN/PAI-1, or PDK-1/PAI-1 24 hours after 20 Gy (D). Representative western blots of phospho-Akt, total Akt, p65/RelA, phospho-ERK1/2, PTEN, BCL-2 and BCL-XL in HUVECs transfected with siRNA PTEN, PDK-1 and/or siRNA PAI-1 24 hours after 20 Gy(E) .