An important role for the CD40–CD40L axis in T1D development has been already shown (55, 57): for example, diabetes did not develop in CD40L–/– NOD mice (56) and treatment with anti-CD40L mAb (54, 94) or CD40 peptide-inhibitors (60) abrogated the disease in regular NOD mice if treatment was initiated early enough. The gene discussed is CD40; the disease is type 1 diabetes mellitus.