PDCD1 and neoplasm: In the core region and the invasive edge of GPNMB-WT tumors, we detected higher levels of PD-1+ T cells (Core: WT = 2.4% ± 1.22% SD vs. KO = 0.44% ± 0.36% SD; p = 0.0018; Invasive edge: WT = 2.5% ± 1.2% SD vs. KO = 0.72% ± 0.29% SD; p = 0.0027) compared to the tumor tissue of KO (Fig. 7D).