Proto-oncogenes have been shown to play a critical role in cell growth and differentiation via signal transduction pathways. Oncogenes, either by enhanced gene expression or altered gene expression, can trigger cellular transformation. In this study, the role of oncogenes was defined in drug-resistant human ovarian carcinoma cells. In both multidrug resistant (actinomycin D) cells and non-multidrug-resistant (cisplatin) cells, Northern analyses demonstrated enhanced gene expression for the following oncogenes: c-fos, c-jun, H-ras, and p53. Based on these findings, strategies are discussed for the use of ribozymes, catalytic RNAs, to suppress gene expression and reverse the observed drug resistance.