For instance, while circ_0091570 has been found to suppress HCC progression by sponging miR-1307 [11] and circMTO1 inhibits HCC progression through targeting miR-9/p21 axis [13], circSLC3A2 has been reported to promote HCC progression by sponging miR-490-3p and regulating PPM1F expression [14]. This evidence concerns the gene PPM1F and hepatocellular carcinoma.