PHGDH and hepatocellular carcinoma: In support of this observation, immunohistochemistry (IHC) analysis of 42 paired HCC samples (cohort 3) using two different commercial PHGDH antibodies demonstrated that the PHGDH protein level was profoundly downregulated in HCC tissues compare with normal tissues (Fig. 1d, e, Supplementary Fig. 2c, d).