9408269 Eldon ABSTRACT Once an egg cell divides, the two cells communicate with each other. If separated they would each divide to make a complete organism, but if they remain together, each contributes to half the organism. How and what embryonic cells signal to each other, then, is critical for normal development. Dr. Eldon is using embryonic development in the fruit fly, Drosophila melanogaster, to study a protein that may mediate communication between cells. From this study we hope to learn how signals between cells are transmitted and received.