In addition, we show that border-forming astroglia derived from either grafted NPC or host proliferating astrocytes, as well as serum-exposed NPC in vitro, all upregulate the transcription regulator Id3, which is also expressed by astroglial limitans borders along meninges and large vessels in healthy tissue but is rare among other astrocytes. This evidence concerns the gene ID3 and nasopharyngeal carcinoma.