Intercellular communication: Relative importance of cellular adhesion and paracrine signaling to hormonal gene expression

Although there is a consensus that a cell's microenvironment can have a dramatic influence on its ability to express a particular gene, the relative contribution of physical interaction (cell to cell adhesion) and paracrine signaling to this phenomenon has been difficult to discern. Here, we addressed this problem in mammotropes by making ''real-time'' measurements of prolactin (PRL) gene expression followed by immunocytochemistry (for post facto identification of a neighbor's phenotype). Our results show that it is the nature (phenotype) rather than the physical presence of a neighboring cell that dictates the degree to which the PRL gene is expressed.