Although overexpression of Notch 1 mRNA or protein has not been found in ovarian tumours, our data point to a possible role of the Notch pathway in ovarian cancer formation: our transfection experiments indicate, that activation of the Notch pathway could contribute to the malignant phenotype by maintaining proliferative activity against growth control signals and by promoting cell survival. The gene discussed is NOTCH1; the disease is ovarian cancer.