To further confirm the down-regulation of SFRP1 at protein levels, immunohistochemical staining was performed on an additional 100 pairs of HCC specimens and corresponding adjacent non-cancerous livers using tissue array (Shanghai OUTDO Biotech Co, LTD, China), where immunohistochemical-staining intensity was scored on a scale of 1+ to 3+. Here, SFRP1 is linked to hepatocellular carcinoma.