(a) Ba/F3 cells expressing FOXO3(A3)-ER were stimulated with 4-OHT in the presence of mIL-3. Cell lysates were analysed for glutamine synthetase (GS) activity in an enzyme assay (left). In addition, the expression of glutamine synthetase, p27 and actin was determined using western blot (right). Shown are the mean ± s.e.m. (n=3) and representative blots of these experiments. **P0.01. 