While no previous study has specifically examined miR-22 expression in CD133+ GSCs or GBM tissue, a study by Zekri et al. reported that miR-22 expression was reduced in CD133+ primary hepatocellular carcinoma cells compared with primary hepatocellular carcinoma cells (Zekri et al., 2018). The gene discussed is PROM1; the disease is hepatocellular carcinoma.