Fig. 4. Transcriptional and translational dependency of the effects of growth factors. In the presence of 1 µM actinomycin D (A) or 1 µM cycloheximide (B), astrocytes were treated with 3 ng/ml bFGF, 100 ng/ml IGF-1, or 30 ng/ml EGF for 24 hours. The facilitatory effects of the growth factors on glutamate transport activity were completely blocked by either the translational inhibitor cycloheximide or the transcriptional inhibitor actinomycin D. (*p<0.05; **p<0.01 vs control; ^##p<0.01 vs the corresponding growth factor, Tukey’s test following ANOVA). Data represent means±s.e.m. of 4 cultures.