MTOR and nasopharyngeal carcinoma: Circ-RNF13 prolongs the half-life of SUMO2 by binding to the 3′ untranslated regions (3′-UTR) of SUMO2 gene, which leads to sumoylation of GLUT1 and ubiquitination to regulate the AMPK-mtor pathway, ultimately promoting proliferation and metastasis of nasopharyngeal carcinoma (NPC) (Mo et al., 2021).