MDH1 and hepatocellular carcinoma: In addition to FH, the KEGG enrichment analysis results following MS identification indicate that PDHB, PDHA1, PC, MDH1, DLD, and DLAT are also key proteins involved in carbon metabolism, the TCA cycle, and pyruvate metabolism in cancers, including HCC, ICC, breast cancer, and pancreatic ductal cancer (33, 34, 35, 36, 37).