CTLA4 and neoplasm: Moreover, mice treated with anti-CTLA-4 developed long-lasting protective immunity, and in vitro CTLA-4 blockade inhibited the suppressor activity of UV-induced Tregs, suggesting that anti-CTLA-4-treated mice were protected from tumor growth due to the inhibition of Treg function in the TME (Loser et al., 2005; Figure 2A).