PTPN11 and hepatocellular carcinoma: Supporting our findings, PTP4A1 has previously been shown to protect RIG-I from SHP2/PTPN11-dependent degradation, and knock-out of PTP4A1 reduced RIG-I levels and abolished RIG-I-dependent upregulation of IFNB1 in HepG2 hepatocellular carcinoma cells.62