Fourteen days after M‐CSF‐supported HCT and after an additional 1.5 days of MCMV or mock infection, spleen NK1.1+ cells showed increased expression of the immature NK cell transcription factors Ikaros, Id2, Runx3, Gata3, and Tbet as well as the mature NK cell transcription factor Eomes after exposure to MCMV (Fig 2E). This evidence concerns the gene TBX21 and infection.