On the other hand, pro-tumorigenic activities of DCs can be adopted by PD-1-expressing DCs, which accumulate in the tumor and inactivate CD8+ T cells [98]; arginase-expressing DCs, which causes arginine deprivation leading to the inhibition of CD4+ T cell proliferation [99] or reactive oxygen species (ROS)-mediated inhibition of CD8+ T cells [100]. The gene discussed is CD4; the disease is neoplasm.