HIF1A and glioblastoma: Human foreskin fibroblasts (HFF) and U251 malignant glioblastoma cells were infected with the clinical HCMV-Titan strain (Titan WT) and its US28 deletion mutant (Titan ΔUS28) [18] at a multiplicity of infection (MOI) of 2 and assessed for viral protein (Immediate early antigen (IEA) and US28) expression and HIF-1 activity 48 hours post-infection (Figure 6).