BCAT1 and invasive carcinoma: Here, we further performed IHC analysis of different stages of NPC and found that BCAT1 protein level increased in the low-to-moderate grade atypical hyperplasia tissues as well as high-grade atypical hyperplasia tissues, in situ and invasive carcinomas, suggesting that BCAT1 overexpression may be an important early event in NPC occurrence and maintain throughout NPC progression.