Presents research which identified cdc24 alleles that do not affect vegetative growth but drastically reduce the ability of yeast cells to mate, in Saccharomyces cerevisiae. Role of Rho-family of GTPases and their regulators; Haploid cells in budding Saccharomyces; Behavior of mutants; How mutants are specifically defective; Tie between receptor-mediated activation and oriented cell growth.