P73 protein is a structural and functional homologue of p53, a tumor suppressor gene. In this study, The p73 protein, p19ras, by the yeast two-hybrid screening method. Alternative splicing of the proto-oncogene H-ras pre-mRNA has led to two distinct transcripts, Ras proteins are known to be small membrane-localized guanine nucleotide-binding proteins. However, unlike other Ras proteins, p19ras is localized in the nucleus and the cytosol and its interaction with P73 protein occurred exclusively in the nucleus. Oncogenic MDM2 (mouse double minutes 2) is a known repressor of p73 transcriptional activity. In this study, when p19ras was bound to MDM2, it further inhibited the association of MDM2 to the p73 protein. Therefore, this study presents a novel pathway of Ras signaling that occurs in the nucleus, involving p19ras and p73.