PCNA and hepatocellular carcinoma: After using three siRNAs to silence circMMP11 expression in Huh7 and Hep3B cells (Figure 2a), we found that its knockdown inhibited the HCC cell viability (Figure 2b) with decreased numbers of migratory and invasive cells (Figure 2c and d), as well as the downregulated protein and mRNA levels of PCNA and MMP-2 (Figure 2e).