Hi Axel, must it be inverse PCR? Or try this: P.D. Siebert, A. Chenchik, D. E. Kellogg, K. A. Lukyanov, and S. A. Lukyanov. An improved PCR method for walking in uncloned genomic DNA. Nucleic Acids Res 23:1087-1088, 1995. It works. There is also a kit available from Clontech using this method, but you can cook it yourself. It works. Best regards Nicolas