PHGDH and colorectal carcinoma: In addition, we demonstrated that high levels of PHGDH confer a more aggressive phenotype to CRC cells as shown by increased colony-forming ability after 5-FU treatment in RKO OE PHGDH cells with respect to RKO, besides HCT8 shPHGDH cells are more sensitive to 5-FU toxic effect than parental cells and hence exhibit a decreased ability to form colonies (Fig. 3G).