SMAD4 and infection: Indeed, there are fewer Smad4-deficient Kb-ova+CD8+ splenic T cells than competing Smad4-sufficient counterparts in chimeras 35 days post infection, while the frequencies and numbers of Kb-ova+CD8+ splenic T cells are comparable between Smad4co/co;Lck-Cre mice and their littermate controls at the same time point.