PSAT1 and liver cancer: Phgdh and Psat1 are key enzymes that mediate the first two steps of serine (Ser) biosynthesis (Figure 2A).[22] To examine the functional roles of Phgdh in liver cancer, we induced liver tumorigenesis in Phgdhfl/fl (wild‐type, WT) and PhgdhLKO (liver‐specific knockout) mice by hydrodynamic injection.