Interleukin 23 (IL-23) is a cytokine protein and intricate member of the immune response. Composed of IL-23A and the p40 subunit of IL-12 (IL-12B). Agonist of the receptor formed by IL-12RB1 and IL-23R. Responsible for activation of STAT4 and production of IFNG, acting preferentially on CDR(+) T cells. Activates the JAK-STAT pathway, promoting production of pro-inflammatory cytokines. May be implicated in autoimmune inflammatory diseases and tumorigenesis.