This grant proposal falls into two parts. We want to define as completely as possible the organization of integrated hepatitis B viral DNA sequences in a number of hepatocellular carcinomas (HCC). We want to find out if there are common features such as sites of integration, homologies between host and cellular sequences; whether or not this cellular DNA is irreversibly deleted; if there are oncogenes in flanking cellular sequences and if any HBV gene products are expressed in HCC cells. We will approach these questions primarily by molecular cloning the subsequent analyses by blotting, subcloning, electron microscopy and DNA sequencing. Secondly based on our preliminary results we want to molecularly clone out a cellular oncogene from HCC DNA that transforms NIH3T3 cells and find out what the difference is to its normal allele. Also we want to try transfection other cells by newer transfection protocols. In addition we want to screen a number of HCCs (of different kinds) to determine whether there is oncogene amplification, translocation orenhanced transcription. These tasks will be approached by a combination of DNA transfection, molecular cloning, DNA sequencing and DNA and RNA blotting.