CD44 and glioblastoma: Moreover, qRT-PCR and western blot analysis showed that the K-RAS and CD44 expression were increased in the irradiated-U87MG cells, while when we knocked down the K-RAS expression with si-RNA in irradiated-U87MG cells, the CD44 expression was decreased compared to the control groups (Figure 2G,H); however, CD133 which is a marker of stemness was partially induced by IR, but not significantly decreased by knock-down of K-RAS expression in IR-treated GBM cells (Figure 2I).