Although the thyroid origin of ARO cells has been recently questioned [35], our results suggest that ROS generation might be implicated in the cytotoxic response of some cancer cells to bortezomib and ability of cancer cells to induce GCL and subsequent GSH levels, thereby scavenging ROS is, at least in part, involved the cytotoxic responses to bortezomib exposure. The gene discussed is GCLC; the disease is cancer.