However, in our GBM cell lines, aberrant staining and localization of H3.3 S31 phosphorylation along the chromosome arms was not specific to ALT but present in both ALT-positive HSJD-GBM002 cells and telomerase-positive R0315-GBM cells (Figure S2), suggesting that H3.3 S31 phosphorylation is not specifically required for pHGG ALT cells survival. This evidence concerns the gene GPT and glioblastoma.