CDKN2A and glioblastoma: Thus, up to 50% of the glioblastoma cell lines show a deletion in CDKN2a, coding for p16INK4A and p14ARF [51] and, according to the PanCancer atlas, 56% of glioblastoma display homozygous deletion of this gene (https://www.cbioportal.org/study/summary?id=gbm_tcga_pan_can_atlas_2018), which is the most frequently deleted gene in glioblastoma.