Next, exosomes and miR-21 inhibitors were injected with HCC cells into nude mice, and the results showed that the growth rate and size of tumors were only slightly higher than those of the group injected with HCC cells alone (Fig. 8a-b), and the expression of miR-21, PTEN, PTENp1, TET1, TET2 and TET3 was recovered (Fig. 8c-e). The gene discussed is TET1; the disease is hepatocellular carcinoma.