GIPC2 and neoplasm: Since aberrant promoter methylation was a well-recognized epigenetic mechanism involved in tumor suppressor gene silencing in cancers25, we determined the methylation levels of GIPC2 promoter in PPGL samples by MALDI-TOF mass spectrometry (Sequenom EpiTYPER) and found significantly higher levels of methylation in the PPGL samples than normal tissues (Fig. 1G), as well as a negative correlation between GIPC2 mRNA expression and methylation level (Fig. 1H).