Slug is overexpressed in glioblastoma and induced by EGF. A) upper panelWestern blot analysis of protein isolates derived from 6 human glioblastoma (GBM) and 3 human non-tumor brain (NB) specimens. Blots were stained using a specific anti-Slug antibody. β-actin was used as an internal reference for normalization. The Western blot analysis showed low or absent Slug protein expression in all three non-tumor brain specimens and increased Slug expression in five of six GBM specimens. lower panel mRNA was isolated from the same tumor specimens used in the upper panel and quantitative Real-time PCR for SNAI2 mRNA was performed as described. Data shown are the mean of three replicates. B) upper panel Slug protein was isolated from U251 human GBM cells after exposure to EGF (50 or 100 ng/ml) for 4 hours and assayed by Western blot. β-actin was used as an internal reference for normalization. lower panel Real-time PCR analysis of SNAI2 mRNA from the same samples displayed in the upper panel. Data shown are mean ± SEM of three replicates.