Characterizing the consequences of mutated Ras/LET-60 on the development of the C. elegans vulva has provided critical insights into the role of Ras in normal animal development. Furthermore, double mutant analysis revealed the role of Ras relative to other components of growth factor signal transduction. Here we describe the combined use of principles of parallelism and epistasis to investigate the use of different Ras effectors, Raf and RalGEF>Ral, during the development of the vulva and other tissues. We additionally describe the use of these principles to delineate the function of the close Ras relative, RAP-1. The worm continues to lead the way in clarifying otherwise poorly understood functions of Ras during animal development.
