C6 glioma cell cultures differentiated with retinoic acid (10microM) were exposed to NMDA (100microM) or to antagonist MK-801 (200nM) prior to treatment with NMDA and cells were harvested after 24h of treatment to study the expression of total NCAM, PSA-NCAM, nuclear factor kappaB (NF-kappaB) and activator protein-1 (AP-1) by Western blotting and dual immunocytofluorescence and expression of PST mRNA by fluorescent in situ hybridization (FISH).     ///    We report here the transcriptional regulation of PSA-NCAM expression by subtoxic dose of NMDA in retinoic acid differentiated C6 glioma cell cultures.     ///    "Significant increase in the levels of PSA-NCAM, NF-kappaB, AP-1 and PST mRNA was observed in NMDA treated cultures. "    ///    The results elucidate the possible cellular and molecular mechanisms of regulation of PSA-NCAM expression in astroglial cultures by extracellular signals..     ///    Transcriptional regulation of PSA-NCAM expression by NMDA receptor activation in RA-differentiated C6 glioma cultures..     ///    "Control of polysialylated neural cell adhesion molecule (PSA-NCAM) expression by NMDA receptor activation has been described in several systems, suggesting a functional link between these two proteins. "