Actin cytoskeleton is a complex and dynamic network of filaments maintaining cell shape, tension, contractility, adhesion, migration, and intracellular trafficking. The dynamic properties of the actin cytoskeleton are regulated by variety of actin-binding proteins. Access of actin-binding proteins to actin filaments is controlled by tropomyosins. In humans, four TPM genes produce by alternative splicing more than 40 isoforms with non-redundant functions. Tpm2.3 isoform remains largely uncharacterized till now. Our preliminary data revealed that Tpm2.3 is a dominant Tpm2 isoform in osteosarcoma cell lines and that its downregulation is associated with their enhanced metastatic potential. This study is therefore designed to determine the interactions of Tpm2.3 with actin filaments and key actin-interacting proteins and thus reveal its function in regulation of actin dynamics and formation of cellular actin structures in osteosarcoma cells with he ultimate aim to identify molecular mechanisms used by Tpm2.3 in modulation of osteosarcoma growth, metastasis, survival and mechanosensing.