Recently, major breakthroughs have occured in understanding growth factor signal transduction. Three protein targets of the platelet derived growth factor receptor with enzymatic activities relevant to cell signalling have been discovered: phospholipase C, c-raf serine kinase and phosphatidylinositol-3kinase. Other protein-tyrosine kinases activate subsets of these enzymes. Another exciting development is the discovery that certain genes which encode G protein-linked receptors transform cells in culture. Finally, much progress has been made in determining the role of small GTP binding proteins (ras like) in cell growth and transfomation. The major problem is to determine what cellular signalling systems are critical for growth responses. A related, and more approachable problem is the biochemical mechanism by which growth factor receptors turn on secondary responses such as activation of serine kinases and stimulation of phosphatidylinositol turnover. The goal of the meeting is to approach these problems by bringing together those scientists who have made key discoveries suggesting new links between established fields. For example, the session on G protein-linked receptors will emphasize the subject of receptors whose genes have oncogenic potential and the session on cytoplasmic serine kinases will focus on the mechanisms by which growth factor receptors regulate serine kinases.