Indeed, the addition of B7-H4.Ig protein inhibited the anti-CD3–induced proliferation of activated T cells from patients with type 1 diabetes (T1D), arresting CD4+ T cell cycle progression in G0/G1 phase and inducing apoptosis of both activated CD4+ and CD8+ T cells from these patients. Here, VTCN1 is linked to type 1 diabetes mellitus.