PGK2 and central nervous system cancer: Furthermore, among these 69 cell lines, there were three glioma cell lines (U138MG, U251MG, and U87MG), and the mRNA level of PGK1 was significantly higher than that of PGK2. This profile suggested that PGK1, but not PGK2, is the responsible driver gene in glioma (Figure 3D).