NOS2 and neoplasm: This more focused approach defines a spatial relationship between tumor NOS2 and COX2 expression and CD8+ T cells where restricted CD8+ T cells that are excluded from the tumor are associated with elevated tumor NOS2 expression, whereas abated CD8+ T-cell penetration into the tumor core corresponds with tumor COX2-expressing immune desert regions (Fig. 3E–3G; Supplementary Fig. S5A–S5C).