Our groups and others have shown that all trans retinoic acid (ATRA) can modify the immunogenicity of tumor cells both in vitro and in vivo through differential regulation of MHC class I and intercellular adhesion molecule-1 (ICAM-1) as well as increase the sensitivity of glioblastoma to NK-cells [27,28]. The gene discussed is ICAM1; the disease is glioblastoma.