However, studies which have shown a potential contribution of HSD17B1 in disturbed E2/E1 ratio were performed by Verma et al. Immunohistological analyses have confirmed the presence of HSD17B1 in the cytoplasm of carcinoma cells in 85% of the investigated samples, while immunostaining of normal bronchial epithelial cells has rarely shown a weak positive signal. This evidence concerns the gene HSD17B1 and carcinoma.