Th9 cells have been receiving much attention recently due to the fact that this CD4+ T cell subset and its featured cytokine IL-9 exhibit unprecedented anti-tumor immunity.100,479 High frequency of Th9 cells was found positively correlated with better prognosis in NSCLC patients.520 The potent anti-tumor activity of Th9 cells relies on both direct tumor cell killing and indirect roles in shaping anti-tumor immunity. The gene discussed is CD4; the disease is neoplasm.