CD28 and neoplasm: To determine whether the mechanism by which SM16 induces anti-tumor response involves the inhibition of de novo Treg generation, we first tested its capacity to block TGF-β-induced Treg generation from in vitro CD3/CD28-activated CD4+CD25– and CD4+CD25–GFP– T cells from BALB/c and FoxP3eGFP donors, respectively.