Prokaryotic expression of mpIL-11. A Phylogenetic analysis and B amino acid (aa) sequence homologies of pIL-11 in comparison with other mammalian IL-11 molecules (monkey, human, mouse, bovine, chicken and sheep). Phylogenetic analysis based on the aa sequence of the IL-11 was constructed using MEGA version 5.0 software, utilizing the neighbor-joining method and bootstrapping for 1000 replicates with a value > 70%, in order to determine the percentage reliability of each internal node. The amino acid (aa) sequence homologies among the species were analyzed using the MegAlign program of DNAstar (DNAstar Inc.). C The protein mpIL-11 containing 600 bp was amplified specifically from mRNA of pig intestines and cloned into E. coli-expressing vector pET-32a. D SDS-PAGE analysis of the expression and purification of mpIL-11 from E. coli BL21(DE3)/pET-32a. 1: total protein of empty pET-30a vector; 2: protein supernatant including His-Trx-pIL-11; 3: affinity-purified His-Trx-pIL-11 protein; 4: unlabeled pIL-11 protein after enterokinase digestion. E A similar protein sample order to that of D was determined through Western blotting using a monoclonal antibody against His protein.