3. Results 3.1. 20E Down-Regulates ROS Levels and Induces the Expression of Antioxidative Response Genes Elevated levels of intracellular ROS are known to be one of the reasons for genomic instability and, hence, carcinogenesis [29]. Several published reports have written about the ROS-scavenger and antioxidant properties of 20E in several in vitro [30,31] and in vivo systems [32,33]. Thus, we decided to elucidate whether 20E possesses antioxidant properties in lung cancer cells.