CTLA4 and neoplasm: In addition, expression of the inhibitory B7-H4 receptor by TAMs was found to inhibit antigen-specific T-cell responses in human ovarian cancer, while B7-H4 blockade is capable of restoring the T-cell stimulating capacity of macrophages and contributes to tumor regression in vivo.101 Notably, as PD-1 and CTLA-4 are expressed by activated, tumor-reactive T cells, TAM-mediated checkpoint regulation suppresses the adaptive cellular immune response most capable of destroying tumors.