CD8+T-cells are key in cancer defense, maturing into cytotoxic cells through TCR engagement with MHC-II on APCs, supported by co-stimulatory signals (CD28/CD80/CD86) and cytokines like IL-2, IFN-γ, and IL-9 from Th1 and Th9 cells (26, 33, 35). The gene discussed is IL9; the disease is cancer.