The present invention relates to oligonucleotides having the sequence of an untranslated region (UTR) of mRNA from a housekeeping gene and which can modulate the tumorigenicity of neoplastic cells. The present invention further provides pharmaceutical compositions and methods of inhibiting the growth of neoplastic/malignant cells in a mammal with oligonucleotides having sequences of untranslated regions of the mRNA of housekeeping genes. In a preferred embodiment the UTR is the 3'-UTR and the housekeeping gene is ribonucleotide reductase and its regulatory sequences.