Figure 4.

MAPK, but not PI3K signalling is upregulated in UroIICRE⁺ β-catenin^exon3/exon3 H-Ras^Q61L bladder tumours. Immunoblotting demonstrates upregulation of pMEK1/2 and pERK1/2 in the UroIICRE⁺β-catenin^exon3/exon3H-Ras^Q61L tumours, but not pAKT, which is upregulated in the UroIICRE⁺β-catenin^exon3/exon3Pten^fl/fl (but not pMEK1/2 or pERK1/2). We demonstrate that MEK inhibition can regress the UroIICRE⁺β-catenin^exon3/exon3H-Ras^Q61L tumours in terms of size and proliferation (b–c) (P<0.05, Mann–Whitney). We see no difference in the UroIICRE⁺β-catenin^exon3/exon3Pten^fl/fl tumour size nor proliferation after MEK inhibition (b–c). We also notice a reduction in pERK1/2 and pMEK1/2 protein levels on IHC in the UroIICRE⁺β-catenin^exon3/exon3H-Ras^Q61L tumours (d–e) (P<0.05, Mann–Whitney). Uβ H-Ras^Q61L (UroIICRE⁺β-catenin^exon3/exon3H-Ras^Q61L) and Uβ Pten^fl/fl (UroIICRE⁺β-catenin^exon3/exon3Pten^fl/fl)