Figure 6.

Effect of FTI and PD-98059 on TGFβRII and VEGF expression in RIE-Ras cells. (A) RIE-Ras cells were treated for 48 hours with the concentration of FTI (L739,749) and PD-98059 shown. Poly(A) RNA was isolated and Northern blots were prepared. Membranes were probed with ³²P cDNA complementary to TGFβRII, VEGF and 1B15. Autoradiograms were scanned and quantitated by laser densitometry. The signals in each lane were normalized to the respective level of 1B15 expression and plotted relative to expression in untreated RIE-Ras cells. Both compounds are suspended in DMSO, which has no apparent effect on expression of either mRNA species. This experiment was repeated twice. Similar results were seen in RIE-Sos cells. Solid bars: TGFβRII expression; hatched bars VEGF expression. (B) RIE-Ras cells were treated with 25 µM FTI (L739,749) for 24 and 48 hours as shown and protein isolates were subjected to Western analysis as described in Materials and Methods. In separate experiments, the cells were treated with FTI for 48 hours followed by removal (R) of the inhibitor for 24 or 48 hours as shown. (C) Confluent RIE-Ras monolayers were treated with vehicle, 25 µM L739,749 or 25 µM PD-98059 for 48 hours. Crosslinking was performed as described in Materials and Methods. Unlabeled TGFβ1 was included in assays (+) to control for specificity of binding. Similar results were observed in RIE-Sos cells.