ID1 and neoplasm: We treated established LLC tumor-bearing mice (n per group = 8; extreme groups: Id1+/+/DPBS injected with pLKO-sc LLC; Id1+/+/anti-PD-1 injected with pLKO-sc LLC; Id1-/-/DPBS injected with Id1sh-LLC; Id1-/-/anti-PD-1 injected with Id1sh-LLC) with anti-PD1 therapy or vehicle during a defined period of time.