The results of the analysis of proliferative activity, apoptosis rate (TUNEL staining), and density of tumor vessels (CD34 staining) in tumors harvested from the three groups showed a higher MIB1 index (by about 22%, p = 0.01) and blood vessel density (by about 40%, p = 0.045) and lower levels of TUNEL-positive apoptosis (by about 40%, p = 0.04) in tumors that were formed in the hemisphere after exposure to X-ray radiation (IR/Ipsi-tumor group) than in the control group. This evidence concerns the gene MIB1 and neoplasm.