Cancer cells are often addicted to de novo serine synthesis to support their survival and rapid proliferation. However, how serine synthesis is regulated in cancer is not well understood. Our recent report demonstrated that protein arginine methyltransferase 1 (PRMT1) is upregulated in hepatocellular carcinoma (HCC) and methylates phosphoglycerate dehydrogenase (PHGDH, the first and rate-limiting enzyme in serine synthesis) at arginine 236, thereby activating PHGDH and promoting serine synthesis. Nevertheless, the mechanisms underlying upregulation of PRMT1 and regulation of PRMT1-PHGDH axis in HCC remain unknown. Here, using label-free quantitative proteomics analysis, we identified the potential interacting proteins of PRMT1.