PD-L1 immunohistochemical staining (IMAGE) Hokkaido University Caption PD-L1 immunohistochemical staining in typical oral malignant melanoma (left) and squamous cell skin cancer (right). The tumor cells are stained brown, indicating that they are PD-L1 positive (Naoya Maekawa, et al. npj Precision Oncology. February 12, 2021). Credit Naoya Maekawa, et al. npj Precision Oncology. February 12, 2021. Usage Restrictions This image is copyrighted but may be used to report this press release if credited as instructed. 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.