ERα expression was not found in normal oral mucosa (n=0/5) and simple hyperplasia (n=0/11) but in four oral precursor lesions (squamous intraepithelial neoplasia, SIN I-III, n=4/35, 11%) and in five OSCC specimen (n=5/46, 11%, Fig. 2). This evidence concerns the gene ESR1 and squamous cell intraepithelial neoplasia.