MT-RNR2 and central nervous system cancer: Orthotopic implantation of Gl261 cells (a mouse glioma cell line; Figures 4E and S2E) did not lead to humanin expression, but injection of hGBM1 (overexpressing HN-WT) into the brain resulted in strong and homogeneous humanin immunopositivity throughout the entire GBM area (Figures 4F and S2C).