Another human cerebral organoid modeling GBM has been developed by targeting an HRasG12V-IRES-tdTomato sequence into the TP53 locus using the CRISPR-Cas9 system [164], which exhibits an increased fraction of tumor cells, accompanied by the expression of the GBM stem cell markers OLIG2, GFAP, and SOX2, and the proliferation marker KI67, indicating the GBM identity. The gene discussed is OLIG2; the disease is glioblastoma.