Support is requested for a Keystone Symposia meeting entitled MicroRNAs and Noncoding RNAs in Cancer, organized by Frank J. Slack, Manel Esteller and Lin He. The meeting will be held in Keystone, Colorado from June 7-12, 2015. MicroRNAs and other noncoding RNAs have recently emerged as key regulators of gene expression during development and are frequently mis-expressed in human disease states, in particular cancer. MicroRNAs act to promote or repress cell proliferation, migration and apoptosis during development, all processes that go awry in cancer. Thus, microRNAs have the ability to behave like oncogenes or tumor suppressors. Their small size and molecular properties make microRNAs amenable as targets and therapeutics in cancer treatment. MicroRNAs thus present a paradigm shift in thinking about gene regulation during development and disease and provide the oncologist with a potentially powerful new battery of agents to diagnose and treat cancer. However, while hundreds of human microRNAs and noncoding RNAs are known, we have a relatively poor understanding of their roles and targets, and there is still a limited literature on using these molecules in the clinic. The specific aims of this meeing serve to address these deficiencies and are as follows: 1) To discuss the exciting biology of microRNAs and noncoding RNAs in controlling developmental and cancer processes like cell proliferation, differentiation, cell cycle, apoptosis and metastasis. This meeting will highlight te best current research into the role that microRNAs play in these fundamental processes and provide the basic understanding that will drive the invention of powerful clinical tools. 2) To review the latest efforts to harness the power of these RNAs as agents in the fight against cancer. Discussions will range from use of microRNAs as diagnostic and prognostic markers in cancer, to SNPs providing risk factors for cancer, to the delivery and effectiveness of small RNA therapeutics in clinically relevant settings. 3) To attract the best researchers working in small RNAs and cancer to one place for critical discussions that will advance the field and accelerate the bench to bedside use of this technology. 4) To provide a stimulating environment where students, postdocs and junior investigators can present and discuss their research with the best minds in the field.