In order to understand the function of a cDNA (c171) associated with the upstream regulatory region of the Hoxa-7, the cDNA was cloned into the pGEX-4T-1 vector to produce it as a GST fusion protein. The size of the fusion protein was determined to be 48-kilodalton (kDa). Sequence analysis revealed that a protein C171 contained one hydrophobic transmembrane domain in the N-terminal region and several putative phosphorylation and glycosylation sites. C171 protein inhibited the bacterial growth within 30 min after induction. The transmission electron microscopic examination revealed that the morphology of the cells expressing C171 was changed dramatically: i.e., unusually elongated phenotype compared with those of controls, and finally leading to a cell death. These results altogether indicate that a trace amount of C171 induces bacterial cell death.