It has been reported that inhibition of PI3K/Akt signaling pathway led to radiosensitize the tumor cell by affecting repair of DNA double-strand breaks via DNA-PKcs, and this pathway inactivates Bad and caspase-9 and activates p21, p27 and Mre11, which are associated with cellular radiosensitivity [21,22]. This evidence concerns the gene CASP9 and neoplasm.