Although increased cell proliferation is a hallmark of cancerous tissues, in some cases, it may actually be protective against tumor growth, according to a new study from Caltech researchers. Using mathematical models, the work suggests a new paradigm for the earliest stages of cancer development. Subsequent experiments in jellyfish, a particularly cancer-resistant model organism, support the idea that high rates of cellular proliferation enable tissues to conduct quality control or “proofreading” in order to destroy cells that could become cancerous.