CD274 and neoplasm: To evaluate the effect of PD-L1-positive TMPs on T-cell activation, TMPs were isolated from untreated or irradiated WT and PD-L1 KO EMT/6, PyMT, and 4T1 tumor cell cultures and mixed with splenocytes freshly extracted from spleens of non-tumor-bearing BALB/c or C57Bl/6 mice.