PHGDH and ovarian cancer: Neither E64D plus pepstatin A nor MG132 altered the different expression of PHGDH in platin-sensitive ovarian cancer cells and their platin-resistant partners compared to the cells treated with the solvent vehicle (Figure 4B), indicating that synthesis, but not degradation of PHGDH might be responsible for upregulation of PHGDH in platin-resistant ovarian cancer cells.