TBXA2R and head and neck squamous cell carcinoma: The average β-values (indicating promoter methylation) for the GPCRs genes were significantly higher in the HNSCC samples than in the normal samples (p < 0.05), except for PTGER4 and TBXA2R. Moreover, we have compared the expression level of the GPCRs genes between HNSCC and normal control using the samples from TCGA database (Supplementary Table S6).