Activated BRK Model (IMAGE) Stowers Institute for Medical Research Caption When SMAD4 is tyrosine phosphorylated by activated BRK, it interacts with chromatin-modifying complexes (such as the Sin3/HDAC, NuRD, and NuA4 histone acetyltransferase complexes) and transcription factors to achieve broader genomic access to regulate gene expression. Credit Washburn Lab Usage Restrictions None 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.