FAS and autoimmune lymphoproliferative syndrome: With virtually no detectable levels of fas protein, these mice develop an ALPS-like phenotype that includes autoimmunity, lymphadenopathy, splenomegaly, and expansion of CD4−/CD8− DNTs and have been used historically to evaluate the potential benefit of other therapeutic candidates (11, 12, 13, 14, 15, 16, 17, 18, 19, 20).