However, the proportion of GFAP‐expressing cells varied markedly in the primary glioblastoma cell lines (Figures 3 and 4A): in 3/15 pGCL, it was high (>50%), in 8/15 pGCL, medium, and in 4/15 pGCL, low (≤10%). Here, GFAP is linked to glioblastoma.