Substantial UV-induced ROS from skin efficiently provoke the ERK, JNK, and p38MAPK pathways to spur diverse cytokines secretion by sensitizing the activator protein (AP)-1 and upregulating the expression of the cyclooxygenase-2 (COX-2) gene, further contributing to a series of molecular events particularly immune suppression, inflammatory response and angiogenesis in skin; these events offer the guarantee for photoaging acceleration and tumour cell infiltration, thereby leading to the invasion and metastasis of light-related skin cancers especially SCC [38]. The gene discussed is PTGS2; the disease is skin cancer.