The coding sequences of cytoplasmic and nuclear variants of lacZ gene were inserted downstream of the human cytomegalovirus immediate-early gene promoter of plasmid pcDNA3.1/myc-His C. The new cytoplasmic and nuclear constricts of E. coli β-galactosidase-coding sequences were introduced into HeLa cells with the aid of linear polyethylenimine and at 2 days post-transfection the cells were stained using 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal).