While high expression of CD24 is associated with tumor cells sensitivity to radiotherapy because CD24(-)/CD44(+) is a tumor stem marker, its low expression or loss in stem-like breast cancer generates radioresistance by inhibiting radiotherapy-induced tumor cell death, because loss of CD24 leads to low level of radiation-induced ROS and decreased genomic instability [107]. The gene discussed is CD24; the disease is breast carcinoma.