We further investigated the protein expression pattern of full length Notch 1 (330–220 kDa), the Notch 1 extracellular domain (Notch 1-EC, 120 kDa) and of the downstream transcription factor HES1 (32 kDa) in 28 of the 32 ovarian tumours (16 ovarian carcinomas, three borderline tumours, nine ovarian adenomas), in three human ovarian cancer cell lines and one ovarian surface epithelium cell line. The gene discussed is NOTCH1; the disease is ovarian carcinoma.