Previously, we reported that sublethal doses of IR induce malignant effects, such as cell invasion, by stimulating the SULF2/β-catenin/STAT3/SOD2/Bcl-XL signaling pathway via p53 in vitro and in vivo; whereas mitochondrial ROS produced by Bcl-XL promote cancer cell invasion via an Src-dependent pathway [5,14,24]. This evidence concerns the gene STAT3 and cancer.