SLIT1 and astrocytoma (excluding glioblastoma): To further ascertain the believability of the IRGP signature in normal human astrocytes and low-grade glioma cells (WHO Grade III, astrocytoma), we performed western blotting analysis and qRT-PCR to investigate the transcription and protein expression levels of four selected IRGs (EGFR, SLIT1, ADRB2, and MSR1) in these cell lines.