NAGS and glioblastoma: Therefore, we queried cBioPortal for the number of glioblastoma, glioblastoma multiforme, lung adenocarcinoma, and stomach adenocarcinoma samples exhibiting NAGS, CPS1, and citrin gene copy number variation (CNV), and whether there is an association between CNVs and mRNA expression of the three genes in the four tumor types (Figure 4).