PGR and squamous cell carcinoma: Ferguson et al. using immunohistochemical analysis in normal laryngeal tissues and laryngeal carcinomas, concluded that ER and PGR were both localized in the nucleus of cells and their expression was primarily in the vocal muscle in contrast to the rest of laryngeal epithelial tissue, and, in addition, no expression was found in squamous cell carcinomas of the larynx and hypopharynx [11].