PHGDH and hepatocellular carcinoma: Wei L et al. identified the first activated enzyme phosphoglycerate dehydrogenase (PHGDH) in the serine synthesis pathway (SSP) as a critical driver of sorafenib resistance through a genome-wide CRISPR-Cas9 screening and verified that the PHGDH inhibitor NCT-503 was synergistic with sorafenib to impair hepatocellular carcinoma (HCC) growth in vivo [38].