Also, MDSCs induced by conditioned medium derived from PIWIL1-overexpressing HCC cells exhibited a higher proliferation rate as detected by BrdU assay (Supplementary Fig. S4h), as well as increased migration ability (Supplementary Fig. S4i), which may resemble the mechanism of PMN-MDSCs assembly in the hepatic tissues surrounding the HCC tumors. This evidence concerns the gene PIWIL1 and hepatocellular carcinoma.