Product Description: Interleukin-9 (IL-9) is a cytokine produced by type 2 T helper (Th2) cells and regulates hematopoietic cells. IL-9 signals through the interleukin-9 receptor (IL9R) to activate STAT signaling. IL-9 functions to induce cell proliferation, prevent cell apoptosis, and is associated with asthma and airway hyperresponsiveness.