Salk Scientists Develop Faster, Safer Method for Producing Stem Cell (image) Salk Institute Caption These are endothelial cells derived by indirect lineage conversion from human fibroblasts (skin cells). Cell nuclei are in blue; proteins that are hallmarks of endothelial cells are green and red. Credit Image: Courtesy of the Salk Institute for Biological Studies Usage Restrictions News media reproduction to illustrate this story permitted with proper attribution as provided above. For one time use only. 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.