RTKN2 and hepatocellular carcinoma: In hepatocellular carcinoma, hsa_circ_104348 facilitates metastasis via the miR-187-3p/Rhotekin 2 (RTKN2) axis; circRNA-SORE induces resistance to sorafenib through miR-103a-2-5p/miR-660-3p; and hsa_circ_0004018 exerts tumor-promoting functions [21–23].