Figure 6
Effect of genistein and PP1 on [3H]thymidine incorporation, EGF-R and ERK1/2 phosphorylation, and Ras activation induced by LTD 4 or EGF. (A-B) Increase of [3H]thymidine incorporation induced by 1 μM LTD4 and 20 ng/ml EGF alone and in combination in the absence and presence of (A) 50 μM genistein or (B) 1 μM PP1 (30 minutes pretreatment). Control is represented by MEM additioned with 1% FBS. The results are presented as mean ± S.E.M. of at least three experiments performed in triplicate on at least two different cell lines. **P < 0.01 (one-way ANOVA). (C) EGF-R phosphorylation induced by 1 μM LTD4 (3 minutes), in the absence and presence of 50 μM genistein or 1 μM PP1 (30 minutes pretreatment). 1 ng/ml EGF was used as an internal control. (D) ERK1/2 phosphorylation induced by 10 nM LTD4 and 0.1 ng/ml EGF (5 minutes) in the absence and presence of 50 μM genistein or 1 μM PP1 (30 minutes pretreatment). E) Increase of Ras-GTP levels induced by 10 nM LTD4 and 10 ng/ml EGF alone and in combination (5 minutes). Activated Ras (p21 Ras-GTP) was co-immunoprecipitated and detected by immunoblotting the same amount of proteins for each sample with a pan-Ras antibody. The results presented are representative of at least three experiments performed on two different cell lines.