Inhibitors of KIAA0175 are provided that reduce the expression or biological activities of KIAA0175, p53 and/or p21 in a mammalian cell. KIAA0175 inhibitors include anti-sense molecules, ribozymes, antibodies and antibody fragments, proteins and polypeptides as well as small molecules. KIAA0175 inhibitors find use in compositions and methods for decreasing KIAA0175, p53 and/or p21 gene expression as well as methods for increasing the chemo and/or radiosensitivity of mammalian cells, including tumor cells, methods for decreasing the side effects of cancer therapy and methods for treating neoplastic diseases.