LIF and infection: The amount of recombinant LIF present in infected cell culture samples was 1 pg/μl in the glioblastoma cell line T98G and 2–3 pg/μl in Vero cells at 24 h after infection at a multiplicity of infection (MOI) of 0.5 PFU/cell, meanwhile the backbone virus HSV-Zeo induced no detectable LIF expression.