ATF4 and anaplastic astrocytoma: Westernblot analysis results showed that UPR related indicators including p-PERK, immunoglobulin heavy chain binding protein (Bip), activating transcription factor 4 (ATF4), and phospho-eukaryotic initiation factor 2α (p-EIF2α) were all highly upregulated in anaplastic astrocytomas (WHO grade III) and glioblatomas (WHO grade IV) compared with nontumor brain tissues, while there was no significant difference of PERK protein level among them (Figure 1 a and Supplementary figure 1).