Figure 2: CD47 signaling controls radiosensitivity. Ionizing radiation induces double strand breaks in DNA, which trigger p53 activation and other damage response pathways that lead to cell death. In the presence of CD47 this involves caspase-dependent apoptosis as well as type III programmed cell death via mitochondria. Down regulation of CD47 by morpholino treatment blocks these death pathways and allows cell survival and continued growth following repair of the radiation damage.