Tumor Drones (image) University of Pennsylvania School of Medicine Share Print E-Mail Caption Secretion of exosomes by tumor cells (lower right) to fight the T cells (upper left). Credit The labs of Wei Guo, PhD, and Xiaowei Xu, MD, PhD, University of Pennsylvania. Usage Restrictions None Share Print E-Mail 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.