We investigated the effect of limonin on the cellular levels of p53 and p65 proteins in ovarian cancer cells and found that the limonin-induced apoptotic cell death was initiated by the activation of the p53 protein, subsequently leading to an increase in the level of p53 as well as to its nuclear translocation, thereby resulting in the activation of proteins involved in the process of apoptosis (Figs. 3 and 4). This evidence concerns the gene TP53 and ovarian carcinoma.