Higher median survival times correlated well with the decrease in tumor cell proliferation (Figures 3D and S4A), U87 parental tumors showing a greater mitotic index (∼15%) than cells expressing IRE1α mutant cells (10.0%, 7.7% and 2.5% of Ki-67 positive cells for K599A, Y892A and K907A variants, respectively). This evidence concerns the gene MKI67 and neoplasm.