To elucidate the role of the 5′ terminal nucleotide present in IVT-derived RNAs on the strength of RIG-I/IFN pathway activation, we transfected IVT short viral RNAs harboring 5′-pppA or 5′-pppG as a 5′ terminal nucleotide into human embryonic kidney HEK293 and lung adenocarcinoma A549 cells. The gene discussed is IFNA1; the disease is lung adenocarcinoma.