After demonstrating that p63 can directly bind the promoter regions of serine de novo and OCM enzymes, we performed a correlation analysis between p63 protein expression and PHGDH, PSAT1, PSPH and MTHFD2 mRNA expression levels in HNSCC (Additional file 1: Figure S3a). Here, MTHFD2 is linked to head and neck squamous cell carcinoma.