PVR and glioblastoma: In the present study, upregulation of CD44 and CD155 was detected in three GBM cell lines (UPAB, UPMC and SNB-19) and a correlation between CD44/CD155 expression and cell invasiveness was observed, i.e., UPMC with the lowest CD44/CD155 level was less invasive compared with UPAB and SNB-19 (data not shown).