CD34 and cancer: Previous studies have indicated that generation of intracellular ROS is crucial for induction of apoptosis by chemotherapeutic agents in various types of cancers.33 To determine whether DS/Cu-induced apoptosis would rely on intracellular ROS production, we thus measured the ROS level in CD34+CD38− KG1α cells after exposed to DS/Cu for 6, 12, 18, 24 h, using the DCFH-DA-based assay.