GPT and neoplasm: By using quantitative methylation-specific PCR (Q-MSP), Misawa et al. [35] identified a methylation concordance between primary tumor samples and plasma ctDNA for ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 1 (ATP2A1), calmodulin-like 5 (CALML5), DnaJ heat shock protein family member C5 gamma (DNAJC5G), glycine N-methyltransferase (GNMT), glutamate-pyruvate transaminase (GPT), and lymphocyte antigen 6 family member D (LY6D) in HPV-associated OPC cases.