Fig. 6. Expression of cyclins is regulated differentially by ERK and PI 3-kinase signalling. Expression pattern of cyclins was assessed following serum starvation (-) or following 16 hour restimulation with 10% (v/v) FCS (+). For inhibitor experiments cells were first pre-treated with inhibitors for 60 minutes prior to serum stimulation. An equal amount of cell lysate was subjected to western blotting for (a) cyclin D1, (b) cyclin E expression and (c) cyclin A expression. (d) ß-Tubluin was used as marker for loading control.