ACE2 and osteosarcoma: Next, we analyzed the mRNA expression of ACE2, ADAM17 and CD9 in datasets of cultured cell lines, including HaCaT cells (keratinocytes), epithelial carcinoma cell lines, such as Caco-2 (colon), MCF-7, MCF-10A, T47D, MDA-MB-231 (breast), HeLa (uterine), PC3 (prostate), and the non-epithelial cancer cell line U-2 OS (osteosarcoma).