MUC4 and hepatocellular carcinoma: We found that specific gene mutations, including those in tumor protein p53 (TP53) and mucin 4 (MUC4), as well as in loci on chromosomes 2p24.1, 4q21.3, 4q35.1, 13q14.2, and 19p13.3, were associated with variations in GPN1 expression in HCC (Figure 6A).