Since it has been shown that bone-forming cells such as osteoblasts and osteocytes express low amounts of Klotho (Raimann et al., 2013; Rhee et al., 2011; Komaba et al., 2017), the Klotho expression in tumor cells may reflect the differentiation of mesenchymal stem cells to osteoblastic lineage cells. The gene discussed is KL; the disease is neoplasm.