Accumulating evidence suggests that many types of cancer cells exhibit increased levels of ROS.9 ROS, like hydrogen peroxide (H2O2) and others, can act as second messengers in cellular signaling.12, 13 ROS regulate protein activity through reversible oxidation of proteins such as tyrosine phosphatases, tyrosine kinases, transcription factors and receptor tyrosine kinases.14, 15 In this study, we found that HOI-02, which contains an NO2 group, could increase the generation of ROS in esophageal cancer cells. The gene discussed is NTRK1; the disease is cancer.