An abnormality in expression of genes encoding proteins responsible for the cell cycle regulation frequently results to a malignant cell transformation and switches the cellular program from differentiation and apoptosis to continuous cell division. To evaluate therapeutic potential resulted from silencing gene expression of key cell circle regulators in different human cancer cells the siRNAs targeted to HER2, protein kinase C (PKC), and cyclin B1 (CCNB1) mRNAs were used. An effective and specific reducing the CCNB1, HER2 or PKC mRNA level was observed through 48 h after the siCycB1, siHER2 or siPKC transfection, respectively. The HER2, PKC, and CCNB1 gene silencing substantially reduced a growth rate of the cell lines, except HL-60, but did not affect the cell death and apoptosis. The best cell division inhibition was induced by the siCycB1 in SK-N-MC cells and by the siPKC in MCF-7 cells. The data obtained suggest the siRNAs selected inhibit the cell division, and the genes investigated may be used as effective targets for curing oncologic diseases.