Fig. 2.

Classification of lncRNAs based on their functional mechanisms. a The multiple functional roles of lncRNAs. In the nucleus, lncRNAs are involved in transcription regulation (activation or repression) via acting as transcription factors, splicing of mRNA, and chromatin modification. In the cytoplasm, they regulate translation by interacting with ribosomes, sponging miRNAs, degrading mRNAs, scaffolding protein interactions, and trafficking transcription factors. Moreover, lncRNAs can be enclosed and released by extracellular vesicles, such as exosomes. b The functional contributions and expression levels of reported lncRNAs in brain tumor