ADA and hepatocellular carcinoma: Recently, circular RNAs (circRNAs) emerged as potential molecules mediating tumor biology and function through multiple mechanisms.12, 13, 14, 15, 16 However, the functions of circRNAs in HCC remained poorly understood.17 Meanwhile, adenosine deaminases that act on RNA (ADAR1) has been well studied in HCC as a tumor promoter by interrupting RNA editing equilibrium.18 Intriguingly, ADAR1 was also reported to be a critical regulator of circRNA formation.19