Interestingly, we demonstrated that MDSC hyperexpansion led to accelerated growth and metastasis of transplanted tumors in young adult M-Traf3-/- mice, implicating that MDSC expansion is not simply a consequence but plays a causal role in tumor progression in aging M-Traf3-/- mice with spontaneous tumor development (27). The gene discussed is TRAF3; the disease is neoplasm.