p75 (image) Salk Institute Share Print E-Mail Caption Salk researchers find that the p75 protein is vital for signaling pain in the nervous system. The presence of p75 (green) and Ret (red) together in some sensory neurons suggests that the proteins may interact with each other. Credit Salk Institute Usage Restrictions with credit and related coverage. Share Print E-Mail 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.