IL-2/STAT5 has an important role in the differentiation and homeostasis of Treg and CD8+ T cells that are the key effector cells of tumor immunity (B. J. Chen et al. 2022; Frantz et al. 2022; Kolios et al. 2021; Rajendeeran and Tenbrock 2021). The gene discussed is CD8A; the disease is neoplasm.