Here, we demonstrate that ADAR2 strongly down-modulates miR-21 and up-regulates PDCD4 protein (PDCD4 is a validated miR-21 target gene [37]) and that this has important consequences in inhibiting glioblastoma cell migration (Figure 8c,d and S6c,d in Additional file 1). This evidence concerns the gene PDCD4 and glioblastoma.