Healthy Breast Tissue (IMAGE) Harvard Medical School Caption In healthy breast tissue, the percentage of cells expressing molecular marker Ki67 (green) and p27 (red) was low. Credit Sung Jin Huh Usage Restrictions Photo may only be used with appropriate photo credit. 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.