(b) Ba/F3 cells expressing FOXO3(A3)-ER were stimulated with 4-OHT for 16 h in the presence of mIL-3 together with MSO, as indicated. Cell lysates were analysed for glutamine synthetase activity in an enzyme assay (left). Furthermore the expression levels of glutamine synthetase, p27 and actin were determined using western blot (right). Shown are the mean ±  s.e.m. (n=3) and representative blots of these experiments. *P0.05, **P0.01. 