The tumor suppressor CYLD is a deubiquitylating enzyme that negatively regulates different signaling pathways by removing lysine 63-linked polyubiquitin chains from several specific substrates. In various tumor types, CYLD loss can lead to cell survival or cell proliferation. In addition to its loss due to mutations, CYLD expression can also be decreased through transcriptional and post-transcriptional regulatory mechanisms. Moreover, as epigenetic repression of CYLD can affect tumor progression in different cancer types, the activation of the CYLD promoter ensures the tight control of an inflammatory response. Recent work also shows that CYLD activity can be governed by different regulatory mechanisms including phosphorylation, thus providing another layer of control for diverse physiological processes. Copyright 2010 Elsevier Ltd. All rights reserved.