The reason for the low expression of SHOX2, RASSF1A and PTGER4 in LC patients is that the development of LC is closely related to the accumulation of multi-gene variants, and the activation of proto-oncogenes promotes the proliferation and growth of cancer cells, which plays an important role in the mechanism of carcinogenesis, and the activation of proto-oncogenes promotes the proliferation and growth of cancer cells, and plays an important role in the mechanism of carcinogenesis. The gene discussed is PTGER4; the disease is cancer.