The present invention relates to novel therapies for cancer and, in particular, to therapies that are particularly suited to tumor cells resistant to other types of therapies such as radiation, chemotherapy, or combinations of both approaches. The invention provides methods for identifying and implementing strategies to inhibit a transcription factor which, in combination with other factors, renders the cells resistant and inhibits apopotosis of the cells. The invention provides an inhibitory ATF2 N-terminal fragment, specifically a fragment corresponding to amino acid residues 50-100 of ATF2 (termed peptide II). The invention provides methods for inhibiting tumor cell growth with such peptides.