Genetic screen for modulators of the Ras/Raf interaction

In order to identify genes modulating the Ras/Raf interaction, an RNAi screen in C. elegans was performed. Knocking down genes in a marker strain was the first step of the screen. The marker strain was generated by crossing a strain expressing a constitutively active form of Ras, which leads to multivulval (MUV) defects, with another strain containing a transcriptonal fusion of cdh-3 to GFP. This GFP-fusion labels the vulval cells in developing worms. RNAi-mediated knockdown of modulators, which contribute to MAPK pathway activation, should influence the MUV phenotype. Furthermore, by use of the Mek-inhibitor U0126, it was shown that alteration of the MAPK pathway results in rescue of the MUV phenotype. Further experiments in the mammalian system were also performed.