RAC1 and atherosclerosis: In another study conducted using human aortic ECs (HAECs), Wu and colleagues found that tumour necrosis factor-α (TNF-α) [102] plays a causal role in atherosclerosis by increasing intracellular ROS through the small GTPase Rac-1, which, in turn, stimulates the expression of VCAM-1 and ICAM-1—which play a major role in the initiation of early atherosclerosis—in HAECs via NF-kB.