Tumour model (IMAGE) University of Göttingen Caption The only way the researchers were able to trigger a rapid burst of cancer cell motion in a stiff collagen matrix was to introduce weak spots in the surrounding 3-D material. The cancer cell nuclei are shown here red and the weaker spots can be seen here as three darker holes. Credit Dr Swetha Raghuraman Usage Restrictions None License Original 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.