PRPF19 and hepatocellular carcinoma: Mechanistically, sorafenib-resistant circRNA from HCC cells (circSORE) binds to Y box binding protein 1 (YBX1), a master oncogenic protein present in the cytoplasm, blocking the nuclear interaction between YBX1 and the E3 ubiquitin ligase pre-RNA processing factor 19 (PRP19), thereby preventing the PRP19-mediated degradation of YBX1.