CD4 and colitis: While apoptosis in each of the three cell lineages shown to contribute to DSS-induced colitis—myeloid cells, enterocytes, and CD4+ T cells—might be expected to be reduced in ΔβΔβ mice vs. +/+ mice, reduced apoptosis only within pathogenic CD4+ T cells would be consistent with worsening of DSS-induced colitis as we observed in ΔβΔβ mice.