To further validate the HDAC1 and C/EBPβ-combined regulation of CD109 transcription, we confirmed protein complex formation between HDAC1 and C/EBPβ in core-like 267 (Fig. 8d) and core-like 1005 GBM spheres (Supplementary Fig. 8b). Here, HDAC1 is linked to glioblastoma.