Exogenous EGR-1 induces growth arrest in glioma primary cell lines and in U251 cells. Left side: growth curves of CRL-8 (upper), LTN-12 (middle), and U251 (lower) following infection at day 0 with either a recombinant adenovirus expressing an EGR-1 transgene (AdGFP-EGR-1), or control vector carrying the GFP gene insert (AdGFP). Cell growth is given by absorbance units of cell lysates pre-treated with sulphorhodamine B. Cell viability exceeded 90% in control vector-infected cell lines. Duplication times are 23 hrs for U251, 66 hrs for CRL-8, and 100 hrs for LTN-12, allowing for differences between cell lines for cell growth (see LTN-12 versus CRL-8 and U251) or for the length of the reported observation period (see U251 versus CRL-8 and LTN-12). Right side: immunoblot analysis of EGR-1 and β-actin protein extracted from CRL-8 (upper), LTN-12 (middle), and U251 (lower) at days 0, 5 and 7 following infection at day 0 with either AdGFP-EGR-1 or control vector.