To further test the negative effect of SFRP1 on the cell growth of HCC cells, the colony formation assay was performed on another HCC cell line, Hep3B, without the significant expression of endogenetic SFRP1, through the transient cell transfection with the same plasmids, pcDNA3.0 with full ORF of SFRP1 and empty vector (Fig. 2C). Here, SFRP1 is linked to hepatocellular carcinoma.