PDCD1 and neoplasm: Isogenic cell lines upon confirmation of STK11 knockout (by immunoblotting for the LKB1 protein) (Additional file 3: Fig. S1B) were implanted into the right flank of syngeneic recipient mice and cohorts of tumor-bearing mice were randomized to be treated with anti-PD-1 antibody or IgG control (Fig. 1B).