ID1 and neoplasm: To define the synergistic effect of Id1 inhibition in tumor cells and PD-1/PD-L1 axis blockade in the in vivo setting, syngeneic models were generated by injection of our three KRAS-mutant murine LUAD cells (Id1sh-cells or pLKO-sc control cells) into the flanks of mice (n per group = 8).