A new study reveals important insights into the molecular mechanisms that underpin the body’s natural defences against the development of skin cancer. The protein CSDE1 coordinates a complex chain of events that enable senescence in skin cells. The senescent cells act as a firewall against cancer, suppressing the formation of tumours. The findings are surprising because CSDE1 has been previously linked to driving the formation of cancers. The results offer new clues into the behavior of skin cancer at the cellular level, paving the way for potential new therapeutic targets to treat the disease.