<prompt> Answer this question truthfullyWhat is Epstein-Barr virus?  <response>: <reason> The Epstein-Barr Virus surface glycoprotein H gH is essential for penetration of B cells but also plays a role in attachment of virus to epithelial cells. In laboratory and animal trials in 2000, it was shown that both antagonism of RA-mediated growth inhibition and promotion of LCL proliferation were efficiently reversed by the glucocorticoid receptor GR antagonist RU486. 