We categorized nine glioblastoma cell lines into four groups based on the expression levels of EGFR and MIG6: (a) EGFR‐positive (EGFR+) and MIG6‐high level (MIG6high); (b) EGFR+ and MIG6‐medium level (MIG6medium); (c) EGFR+ and MIG6‐low level (MIG6low); (d) EGFR‐negative (EGFR−) and MIG6low (Fig. S1A,B). Here, ERRFI1 is linked to glioblastoma.