PHGDH and cancer: PHGDH, the first and rate-limiting enzyme of SSP, has been reported to be overexpressed in multiple cancers, such as breast cancer, melanoma, renal cell carcinoma and non-small cell lung cancer (Possemato et al, 2011; Snell, 1984; Teisseire et al, 2025; Zhang et al, 2017), where it contributes to aggressive phenotypes and resistance to therapy (Mullarky et al, 2016; Yoon et al, 2023).