Drug-resistant Tumors (IMAGE) Salk Institute Caption These tumors with low levels of Fbx6 are unable to degrade the checkpoint protein Chk1 making them resistant to certain cancer drugs. Credit Image: Courtesy of Dr. Youwei Zhang, Case Western Reserve University. Usage Restrictions News media reproduction to illustrate this story permitted with proper attribution as provided above. For 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.