GPT and brain neoplasm: RNA dot blot analysis on total RNA extracted from control, RAS or rad21;RAS brain samples showed that the levels of TERRA in RAS Rad21+/− tumors were similar to those found in control brain and in telomerase+ HeLa cells, much lower than those present in ALT brain tumors (RAS) and U2OS cells (Figure 2I,J, Supplementary Figure S1).