RGS2-mediated inhibition of cellular protein synthesis is independent of eIF2α serine 51 phosphorylation. (A and B) MEF eIF2^S/S (A) and eIF2^A/A (B) cell lines were infected with adenovirus (MOI = 4) encoding RGS4 (control), RGS2, or an RGS2 minigene for 48 h and used in a [³H]leucine protein synthesis assay as described in Materials and methods. The data were calculated as cpm/µg of total protein, normalized as a percentage of control, and are expressed as the mean ± SEM of three independent experiments performed in triplicate. *, P < 0.05 versus control (one-sample t test).