The malignant behavior of glioma cells in the brain appears to be regulated by an HCP5–miR-139–RUNX1 feedback loop, whereby RUNX1 increased the promoter activities and expression of HCP5 that binds to the tumor suppressor miRNA-139 (miR-139) and, therefore, acts as an oncogene. The gene discussed is HCP5; the disease is central nervous system cancer.