CLK1 and glioblastoma: S5B), analysis of the GlioVis Chinese Glioma Genome Atlas (CGGA) dataset shows a significant association of higher expression of CLK2, but not CLK1, CLK3, or CLK4, with poor OS, and CLK2 mRNA expression significantly increases with grade in multiple brain cancers, including GBM (Fig. 4, B and C).