PRL localization or function are missing or mutated. Our study using Drosophila is the first to examine overexpressed PRL in genetically controlled animal model. This system confirms that PRL can function as a growth inhibitor under normal and oncogenic conditions that can be dependent on submembrane distribution. To examine when and where dPRL function may function in vivo, we monitored dPRL-1 subcellular localization throughout Drosophila embryogenesis and larval development. By expressing dPRL-1 under the control of an engrailed promoter, we verified that our dPRL-1 antibody was functional by observing high Danshensu (sodium salt) supplier levels of dPRL-1 protein in the posterior compartments of the embryo epidermis. Prior to NSC 601980 cellularization, dPRL-1 is evenly expressed throughout the syncytium. Following cellularization, dPRL-1 levels are relatively low in the newly formed blastoderm, but can be seen in the cytoplasm. As embryogenesis proceeds, dPRL-1 remains ubiquitously and cytoplasmically expressed, though most abundant in the amnioserosa in later stages of embryogenesis. Analysis of the first through third larval instar tissues showed that dPRL-1 becomes localized to and more abundant at the plasma membrane though cytoplasmic staining is still detected. The larval midgut demonstrated the most dynamic expression, with some cells showing predominant dPRL-1 staining at plasma membrane and others showing very high levels of dPRL-1 in the cytoplasm. dPRL-1 appears to be ubiquitously expressed throughout larval development although with variable levels; the gastric caecum consistently demonstrated very strong staining for dPRL-1, while the larval brain was consistently among the lowest. In the developing eye and wing discs dPRL-1 is most abundant at the plasma membrane. Staining in the developing eye demonstrates that dPRL-1 levels and localization are similar in both actively dividing cells and differentiated cells. Endogenous dPRL-1 is primarily localized to the plasma membrane in epithelial cells of developing larva, and this subcellular localization held true under conditions of overexpression that led to growth inhibition. Past reports have indicated that the C-terminal CAAX motif is a requirement for the addition of a farnesyl tail���� to anchor mammalian PRLs to the membrane. In
