LINC00632 and hepatocellular carcinoma: Recently, studies have shown that circRNAs are abundant and stable in HCC cell exosomes (136), and in vivo and in vitro studies have shown that exosomal circRNAs, such as circPTGR1, Cdr1as, and circDB, were significantly elevated in the serum of HCC patients and promoted HCC cell proliferation and metastasis (124, 136–138).