On the other hand, Nampt inhibition affects serine biosynthesis from glucose via PHGDH, and the PHGDH-high breast cancer cell lines (estrogen receptor absence, basal-like, such as HCC1806) are highly sensitive to Nampt inhibition compared to PHGDH-low cell lines (estrogen receptor absence, mesenchymal, such as MDA-MB-231) [11,42]. The gene discussed is ESR1; the disease is breast cancer.