Activin-A is a transforming growth factor-β superfamily member that is also implicated in the biology of myeloma-related bone disease.9, 20 Transforming growth factor-β pathway proteins, including activin-A, upregulate periostin expression.21 The correlation of activin-A with periostin in our study suggests a possible combining role of the two molecules in the development of bone loss in myeloma patients. Here, POSTN is linked to plasma cell myeloma.