Anti-cancer Surveillance (IMAGE) La Jolla Institute for Immunology Caption Patrolling monocytes (shown in green), a subgroup of white blood cell, block breakaway tumor cells (shown in red) from gaining a foothold in blood vessel walls, where they could gain access to lung tissue and establish metastases. Credit Courtesy of Dr. Richard Hanna, La Jolla Institute for Allergy and Immunology Usage Restrictions Only as part of news stories covering the findings described above; one time use only. 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.