Cancer Cells (IMAGE) Weizmann Institute of Science Caption Cancer cells, left, were pretreated with a drug that blocks the ERK signal, and right, without the pretreatment. Top cells are untreated, while the bottom ones are stimulated. Credit Weizmann Institute of Science Usage Restrictions None 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.