Animals ; Chemotaxis ; physiology ; Dictyostelium ; genetics ; metabolism ; physiology ; Genes, Protozoan ; genetics ; physiology ; Genes, ras ; genetics ; physiology ; Phosphatidylinositol 3-Kinase ; genetics ; metabolism ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; Proto-Oncogene Proteins ; genetics ; metabolism ; Protozoan Proteins ; genetics ; metabolism ; Signal Transduction ; Transcription Factors ; genetics ; metabolism