It was previously shown that 14-3-3 eta is overexpressed in the synovial fluid of patients with joint inflammation, which is often associated with growth failure. In this study, we investigated the role of 14-3-3 eta in chondrogenesis using ATDC5 cells. Upon treatment with TNF-alpha, cells overexpressed 14-3-3 eta with inhibition of chondrogenesis. Chondrogenesis was also inhibited by overexpression of 14-3-3 eta without TNF-a treatment, whereas silencing of 14-3-3 eta promoted chondrogenic differentiation. Further, G1 phase arrest was inhibited by overexpression of 14-3-3 eta. In summary, we suggest that 14-3-3 eta plays a regulatory role in chondrogenic differentiation. (C) 2011 Elsevier Inc. All rights reserved.