DDIT3 and glioblastoma: In highly malignant glioblastomas, the E3 ubiquitin ligase RNF138 has been shown to mediate ribosomal protein S3 (rpS3) ubiquitination, thereby inhibiting rpS3/DDIT3-mediated apoptotic signaling when stimulated by radiation and inducing radioresistance in glioblastoma (GBM) cells [90].