To test the physiological relevance of HIF1α expression in Th9 cells, we performed Th9 cells adoptive transfer experiments in B16-OVA melanoma model, and observed that the anti-tumor activity of Th9 cells was abrogated in the presence of acriflavine (ACF), a HIF1α inhibitor42 (Fig. 4i, j). Here, HIF1A is linked to neoplasm.