Bone morphogenetic protein 2 (BMP2) is a member of the transforming growth factor beta (TGFbeta) superfamily. Here we report a biological function of BMP2. Treatment of human lung carcinoma cell line, A549 cells with BMP2 resulted in inhibition of A549 cell growth in anchorage-dependent and independent growth conditions. Furthermore, BMP2 induced microfilament organization restoration in A549 cells. These changes were also observed in TGFbeta1-treated A549 cells. BMP2 and TGFbeta1 additionally suppressed the transformed phenotypes and restored actin microfilaments in A549 cells. In contrast, activin A, another member of the TGF superfamily did not induce these phenomena. It was also noted that the development of the microfilaments is almost proportional to the extent of the inhibition of cell growth in our system.