With the aim of the secretion of human granulocyte macrophage-colony stimulating factor (hGM-CSF) in Escherichia coli, hGM-CSF cDNA was fused in-frame next to the signal sequence of ST toxin (ST-I) of exteroxigenic E. coli, containing 53 or 19 amino acids of signal peptide. The fused STsig::hGM-CSF coding fragments were inserted into a T7-based expression plasmid. The recombinant plasmids were subjected to expression analysis of hGM-CSF in the BL21(DE3) strain of E. coli under IPTG induction. Based on the results obtained from the protein pattern of the recombinant E. coli under inducing condition, accumulation of the expressed target protein was detected in both cytoplasmic and periplasmic space