Transcription units E1a and E1b of the human adenovirus encode all of the functions needed for the oncogenic transformation of primary rodent cells to cell lines that are immortalized and have altered morphology and growth properties, both in vitro and in vivo. Knowledge of hos these viral genes function to effect such changes should permit elucidation of the molecular mechanisms by which normal cells become neoplastic ans should suggest strategies for controlling the growth of tumor cells. Five or more proteins are encoded by E1a and E1b. The E1a and E1b gene products that are necessary for the different aspects of oncogenic transformation will be identified by transfection of cells with appropriately mutated recombinant DNA molecules. The roles of these E1a and E1b proteins, in transformation will be further studied using antibodies generated by immunization with synthetic peptides corresponding to portions of individual proteins. These antibodies will be used to measure the synthesis and accumulation of E1a and E1b proteins and to study the compartmentalization of these proteins in infected and transformed cells, and to characterize the associations of the E1a and E1b proteins with cellular structures. Particular attention will be paid to the interaction of E1a proteins with nuclear structure. Specific antibodies to E1a proteins will be used to assay for site-specific interaction with viral DNA. Mutation will be made in the E1a-289R protein and used to correlate its transcription-enhancing function with its role in transformation and its localization in the nuclear matrix. These mutations will also be used to search for differential interaction of the E1a-289R protein with different viral promoters, and for possible differential interaction with the cellular genes that are targets of E1a action. Any mutants that interact with different subsets of these target genes would be useful in determining which targets are critically important for oncogenic transformation.