(a) The MV-GFP-HAA-IL-13 retargeted strain has comparable infectivity to the unmodified MV-GFP virus in glioma lines expressing intermediate or high levels of the interleukin-13 (IL-13) receptor α2 (IL-13Rα2) (GBM12, U251, U87), but not in glioma lines expressing low receptor levels (U118, GBM8) as demonstrated by expression of the green fluorescent protein and syncytia formation after viral infection (multiplicity of infection 1). (b) Cytopathic effect in glioma lines after infection with MV-GFP-HAA-IL-13 and MV-GFP was quantitated by trypan blue exclusion assays at multiple time points. There was comparable cytotoxicity between the IL-13 displaying and the unmodified virus in tumor cell lines expressing intermediate or high level of the IL-13Rα2 receptor (GBM12, U251, U87, GBM10, GBM38). Representative data on day 7 are shown. GBM, glioblastoma multiforme.