It is the goal of this study to determine how tumor promoters and other growth promoting agents modulate hormone receptor action in order to understand the processes by which these agents influence all growth the major aim of the research proposed is to characterize the pathways and mechanisms by which nonTPA-type tumor promoters and nonPDGF-like components in the media from v-sis transformed cells alter epidermal growth factor (EGF) receptor properties. In particular, we will determine the effects of these agents on EGF receptor binding and phosphorylation, characterize the mechanism by which these agents modulate EGF receptor action, characterize the signal transduction pathways, and determine the biological relevance of these pathways. Both biochemical and molecular biological approaches will be used to accomplish these aims. An understanding of the factors involved in the regulation of signal-transducing receptors by tumor promoters and other growth promoting agents will provide valuable information regarding mechanisms controlling cell proliferation and transformation and their modulation by environmental factors.