Considering the crucial role that CD8+ T cells play in tumor eradication [38, 39], we next interrogated whether CD4+ T cells that are unresponsive to activin-A signaling in vivo alter the phenotype and activation status of CD8+ T cells infiltrating lung tumors of CD4/ALK4-KO mice compared to their WT counterparts. The gene discussed is CD4; the disease is neoplasm.