Final Report Summary - GRHL1IN SKIN CANCER (Role of the Grhl1 gene in skin cancer.) We discovered that the Grainyhead-like 1 (GRHL1) transcription factor functions as a novel tumor suppressor in the context of chemically induced skin carcinogenesis in a mouse model. We have also found that GRHL1 acts as a tumor suppressor of skin cancer in human patients as well. We characterized molecular mechanisms responsible for the increased susceptibility of Grhl1-null mice to skin cancer. Our findings may impact on our understanding of the biology of skin cancer, and may provide new strategies for both treatment and prevention of skin cancer.