We therefore transiently transfected TYK2-deficient HEK293T or TYK2-deficient U1 fibrosarcoma cells with genes encoding each pair of receptors (IL-10R2 and IL-22R1 for IL-22; IL-10R2 and IL-20R1 for IL-26; IL-10R2 and IL-28R1 for IFN- λ; IL-20R2 and IL-20R1 for IL-19 and IL-20; and IL-20R2 and IL-22R1 for IL-20). Here, TYK2 is linked to fibrosarcoma.