Fig. 3. Tyrosine phosphatase inhibitors prevent p42/p44 MAPKs inactivation in the nucleus. Quiescent CCL39 fibroblast cells were stimulated for 3 hours with 10% serum. Cells were then treated for the indicated times with bpV(phen) 1 mM (a,b,c,d). 0 minutes corresponds to non-treated cells (a). In e and f, cells were treated for 15 minutes with 1 mM estradiol (15 min est) or 30 µM cycloheximide (15 min CHX), respectively, following a 3 hour 10% serum stimulation. Indirect immunofluorescence detection was performed with the monoclonal antibody anti-activated p42/p44 MAPKs.