PTPRG and nasopharyngeal carcinoma: The silencing of TSGs on chromosome 3p, including ADAM, BLU, DLEC1, GNAT1, LARS2, LTF, MLH1, RASSF1A, RAR-β, TIG1, VLH1, PTPRG, and ITGA9, by the phenomenon of DNA aberrant hypermethylation in NPC, seems to be the key role in the mechanism of NPC tumorigenesis, as reported.