Inactivation of Lkb1 (IMAGE) University of Helsinki Caption Scanning electron microscope image shows 2000x magnification of the basement membrane damaged by inactivation of Lkb1-gene. Basement membrane is a matrix of tightly knit protein fibers, hiding mammary epithelial cells under the surface in the figure. On the right side, the basement membrane is intact and the surface is smooth and even. On the left side, the membrane is degraded and damaged. The arrow shows an epithelial cell protruded above the surface of damaged membrane. It is thought that such basement membrane breakdown allows tumor cells to free themselves from epithelial layers and to spread deep in the neighboring tissues. Credit ©Johanna Partanen / University of Helsinki Usage Restrictions The image may only be used with appropriate caption or credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.