PRF1 and neoplasm: Subclusters with Entpd1 expression were assigned as tumor-specific T cells, including Treg (CD4+Foxp3+), CD8+ effector (Gzmb+Prf1+Ifng+), CD8+ effector memory (Cd44+Cd69+), CD8+ exhausted subclusters (Pdcd1+Lag3+Tigit+Havcr2+).