Interleukin 9 (IL9) binds interleukin 9 receptor a chain (IL9R) and the interleukin 2 receptor common gamma chain (IL2RG) to initiate IL9 signaling downstream cascade. IL9R colocalize with Interleukin 2 receptor ? chain and MHC molecules in lipid rafts of human T lymphoma cells (Nizsalˇczki et al. 2014). IL2RG is essential for IL9 dependent growth signal transduction (Kimura et al. 1995). IL9R (glycoprotein of 64 kDa) has saturable and specific binding sites with a Kd of 100 pM (Renauld et al. 1992). The activated IL9R complex recruits tyrosine kinase proteins from the Janus kinase (JAK) family: JAK1 (JAK1) and JAK3 (JAK3) for subsequent activation of the Signal transducer and activator of transcription (STAT) factors STAT1, STAT3 and STAT5. The activated STATs form STAT5 dimers and STAT1:STAT3 heterodimers (Neurath & Finotto 2016, Li & Rostami 2010).