PHGDH and colorectal carcinoma: Moreover, by investigating cell ability to generate secondary colonspheres by serial passages, we noticed that the presence of high levels of PHGDH positively affects CRC cells self-renewal ability as demonstrated by increased the number of P2 colonspheres in RKO OE PHGDH with respect to control cells even following 5-FU treatment, whereas lack of PHGDH profoundly impairs the self-renewal ability of HCT8 cells both in basal and 5-FU treatment conditions (Fig. 4C).