Figure 2.

The molecular roles of circRNAs in the PI3K/AKT/mTOR signaling pathway. The PI3K/AKT/mTOR pathway is the most commonly activated pathway in human cancers. Receptor tyrosine kinase activation and tyrosine phosphorylation of its cytosolic domain or its scaffolding adaptors create binding sites that recruit the lipid kinase PI3K—a regulator of signaling and intracellular vesicular trafficking and cellular processes such as proliferation, survival, and protein synthesis—to the plasma membrane. circRNAs commonly act as ceRNAs of miRs in tumor progression, thus inhibiting the functions of miRs. Nine upregulated and 6 downregulated circRNAs are indicated; 12 circRNAs regulate the PI3K/AKT/mTOR pathway through ceRNA effects. Red: upregulated circRNAs; blue: downregulated circRNAs.