The MPN-RC Tissue Bank provides the infrastructure to transport, receive, process, store, and distribute tissue specimens obtained from patients with myeloproliferative neoplasms (MPN) as well as patients enrolled on clinical trials (Project 4). All specimens have mutational and clinical annotation stored in the web-based data bank maintained by the Biostatistics and Data Management Core D. These specimens are provided to MPN-RC investigators performing translational research for developing innovative therapies (Projects1-3) and to the Biomarker & Bioinformatics Core D to perform biomarker analyses to evaluate the effectiveness of specific therapies to target the MPN hematopoietic stem/progenitor cells. Specimens are also readily available to members of the larger scientific community for translational research.