PDCD1 and neoplasm: Thirty-five mice subcutaneously inoculated with MBT-2 cells were randomly assigned to 5 treatment groups (n = 7): B. longum 420+anti-PD-1 antibody, B. longum 420 alone, B. longum 2012 alone, PBS+anti-PD-1 antibody, and PBS at 7 days after the tumor inoculation.