Protein molecules containing the CPI domain can bind to CAPZ; leucine, arginine, proline, which are 3 highly conserved amino acids exist in the CPI domain (25); thus, we performed a targeted mutation of these three conserved amino acids to alanine in the CPI domain based on the amino acid sequence of FAM21C (26)(Supplementary Figure 1), to further verify whether FAM21C promotes the invasion and migration of HCC cells by binding to CAPZA1. This evidence concerns the gene CAPZA1 and hepatocellular carcinoma.