PDCD1 and neoplasm: To explore how UVR-driven systemic changes impact tumor immunity with and without anti-PD-1 immunotherapy, we compared size-matched MC38 subcutaneous tumors harvested from the UVR-protected flanks of UVR (UVR IgG2a control n=2, UVR anti-PD-1 n=2) and non-UVR animals (non-UVR IgG2a control n=2, non-UVR anti-PD-1 n=2; figure 3).