Using human thyroid cancer cell lines, Dai et al. examined the relationship between Klotho levels and expression of STC isoforms, STC1 and STC2, and found that STC-1 mRNA and protein expression was significantly lower in Klotho-overexpressing cells, and that STC-1 silencing induced apoptosis whilst inhibiting cellular proliferation [77]. Here, STC1 is linked to thyroid gland carcinoma.