NUDT21 and hepatocellular carcinoma: Except this, there are certain small molecular activators or inhibitors targeting the circRNAs signaling pathways in the treatment of HCC, including HNF4a, RBM3, KIAA1429, DHX9, Twist1, nudix hydrolase 21 (NUDT21), andQKI5 (33, 38, 60, 61, 71, 75, 103).