Fig. 2

circMMP9 is oncogenic and associated with proliferation, migration and invasion in GBM cells. a circMMP9 expression was analyzed by qRT-PCR in normal human astrocytes (NHAs) and GBM cells (U251, SHG44, A172, SNB19 and U87) (*P < 0.05, ***P < 0.001). b Schematic representation of circMMP9 and mock plasmid construction. c circMMP9 expression was measured by PCR in the circMMP9 plasmid or mock plasmid-transfected U87 cells using RNase R treatment. d qRT-PCR was performed to detect circMMP9 expression in treated U87 cells (***P < 0.001). e Schematic representation of designed siRNAs (siRNA1 and siRNA2) for circMMP9 at splice junctions. f circMMP9 expression was detected by PCR in circMMP9 siRNA1, siRNA2 or mock-transfected U251 cells with RNase R treatment. g qRT-PCR was performed to analyze circMMP9 expression in treated U251 cells (***P < 0.001). h circMMP9 expression was measured using FISH in transfected U87 and U251 cells. Red represents the circMMP9 probe, while DAPI was used to stain cell nuclei. i-l Cell proliferation abilities were detected by CCK-8 and colony formation assays in transfected U87 and U251 cells (***P < 0.001). m-n Cell morphology was observed under a microscope. Magnification, 100×, 400×. (O-P) Cell migration and invasion abilities were measured with Transwell assays (***P < 0.001)