Figure 3. FGF-induced dephosphorylation of p107 is prevented by protein phosphatase inhibitors and by SV40 small t-antigen (st SV40).

(A) RCS cells were pretreated with either okadaic acid (OA) or Calyculin A 2 hours before FGF treatment. 20 µg of total protein were subjected to SDS-PAGE following inmmunodetection of p107. (B–G) RCS cells were infected with adenoviruses expressing GFP, st SV40 or st SV40 mutant C97S following FGF1 treatment as indicated. (B,C) 20 µg of total protein were used for immmunodetection of (B) st SV40 and (C) p107. Equal amount of protein loading was confirmed by α-actin immunodetection. (D–G) BrdU incorporation assay of FGF treated or untreated RCS cells expressing either GFP, st SV40, or st SV40 C97S mutant. BrdU was detected by using BrdU antibodies (red). Nuclei were stained with DAPI (blue). (D) Summary of results in panels E–G.