Pharmatest offers an in vitro assay for screening potentially estrogenic or anti-estrogenic compounds (either drug candidates or endocrine disruptors). The assay is performed with the mouse mesenchymal progenitor cell line KS483 that is allowed to differentiate into mature osteoblasts capable of forming bone nodules. Compounds that act as estrogens can be identified by measuring their effect on bone formation.

Bone formation is assessed by measuring calcium deposited into the formed bone matrix and compared with bone formation of groups receiving appropriate control substances.