IL24 is a member of the IL10 family of cytokines. It was identified as a gene induced during terminal differentiation in melanoma cells. IL-10B encoded can induce apoptosis selectively in various cancer cells. Overexpression IL-24 leads to elevated expression of several GADD family genes, which correlates with the induction of apoptosis. The phosphorylation of mitogen-activated protein kinase 14 (MAPK7/P38), and heat shock 27kDa protein 1 (HSPB2/HSP27) are found to be induced by this gene in melanoma cells, but not in normal immortal melanocytes. Alternatively spliced transcript variants encoding distinct isoforms have been reported. The glycosylation is essential for activity of IL-24. Functionally, IL-24 has diverse activities. At low concentrations, it induces type I proinflammatory cytokines such as IFN-γ, IL-1β, IL-12 and TNF-α. At high concentration, it is a strong inducer of apoptosis in tumor cells, but not normal cells. mda-7/IL-24 is being hailed as a ‘magic bullet′ for cancer gene therapy. Recombinant human Il-24 produced in yeast is a single, glycosylated, polypeptide chain containing 158 amino acids and having a molecular mass of 18 kDa. As a result of glycosilation, the protein migrates at 19.5 kDa on SDS-PAGE.
