Stimulation of EGR-1 expression by the endogenous gene Western blot of EGR-1 in CRL-8 and FCN-9, established from glioblastoma multiforme and astrocytoma grade III, respectively. EGR-1 protein synthesis was up-regulated by the endogenous gene in the two primary cell cultures after being exposed to different types of external stimuli, suggesting that EGR-1 expression was regulated at the level of transcription. The characteristics of the two cell lines are described in Table 1 (see Additional file 1). Q, cells made quiescent in serum depleted medium for 24–48 hrs; N, cells growing at log phase in medium with 10% serum (control cells); 20% FCS, quiescent cells stimulated with serum enriched medium for 24–48 hrs; Q + UV, quiescent cells stimulated by UV irradiation (40 J/m2); N + UV, exponentially growing cells stimulated by UV irradiation. PMA, quiescent cells stimulated by PMA (100 ng/ml). A typical experiment is shown.