Interleukin 30 (IL-30) forms one chain of the heterodimeric cytokine called interleukin 27 (IL-27), thus it is also called IL27 p28, it predicts a molecular mass of 24.9 kDa. IL-30, the p28 subunit that forms IL-27 together with EBI3 and is also known as IL-27 p28 or IL-27A, has been considered a surrogate to represent IL-27. It was initially thought to be an IL-12-like cytokine promoting Th1 immunity because of its ability to induce T-bet and IL-12Rbeta2 expression through STAT1 activation during Th1 differentiation.