CD4 and neoplasm: Hu et al. 33 showed that oral administration of Lb. plantarum in BALB/c mice inhibited the growth of CT26 cells and prolonged the survival time of tumor-bearing mice by increasing the effector function of CD8+ and infiltration of natural killer (NK) cells into tumor tissues, upregulating IFN-γ and promoting Th1-type CD4+ differentiation.