Based on the result that the circ-0044539-HIF-1α axis regulates exosome production in HCC (Fig. 5C and Table 2), we further investigated the expression of miR-29a-3p in these exosomes and found that miR-29a-3p was enriched in exosomes derived from MHCC97L-circ-0044539 compared with those derived from MHCC97L. This evidence concerns the gene HIF1A and hepatocellular carcinoma.