CD8A and chronic myelogenous leukemia, BCR-ABL1 positive: Mumprecht et al. [140] proved the expression of PD-1 on CML-specific CTLs and the expression of PD-1 ligand (PD-L1) on CML cells in a mouse model, while extending the study to CML patients, who demonstrated increased PD-1 expression on their CD8+ T cells.