In the newly generated IL-27 receptor WSX-1 and TTP double KO mice (WSX-1/TTP double KO or DKO, thereafter), the percentages and numbers of CTLs are reduced compared with Zfp36−/− mice, and the suppressed tumor growth in Zfp36−/− mice is almost completely recovered in WSX-1/TTP double KO mice. The gene discussed is IL27RA; the disease is neoplasm.