METRN and glioblastoma: To verify whether exosomal circ-METRN can still play a sponging role in the high level of miR-4709-3p, we also observed the effect of ldrEXO treatment on the miR-4709-3p level in glioblastoma cells treated with the previous transfection of miR-4709-3p mimics (Figure 4A).