Cytokine that can act as a growth factor for activated T and NK cells, enhance the lytic activity of NK/lymphokine-activated killer cells, and stimulate the production of IFN-gamma by resting PBMC. Disulfide-bonded heterodimer (IL-12 p70) of 40 kDa and 35 kDa subunits. Also secreted as a monomer (By similarity). Belongs to the IL-12B family.