Yet, the protein stability of GRB2 was noticeably enhanced in HUVECs upon treatment with exosomes from HCC cells with highly expressed GP73 (Fig. 5E), along with a decrease in polyubiquitination of GRB2 (Fig. 5F), suggesting that exosomes from GP73 up-regulated HCC cells may stabilize GRB2 by impeding its ubiquitin–proteasome degradation pathway. This evidence concerns the gene GRB2 and hepatocellular carcinoma.