Cloning, expression and purification of F8-IL10. (a) Schematic representation of the cloning strategy of the F8-IL10 fusion protein. (b) SDS-PAGE analysis of purified fusion proteins: lane 1, molecular-weight marker; lanes 2 and 3, F8-IL10 under nonreducing and reducing conditions, respectively. (c) Gel-filtration analysis of affinity-purified F8-IL10. The peak eluting at a retention volume of 12 ml corresponds to the noncovalent homodimeric form of F8-IL10. (d) MC/9 cell proliferation assay. F8-IL10 displayed biological activity comparable with the one of recombinant human IL10 used as a standard in the assay.