We have shown that cytokine-like 1 (Cytl1) is a novel autocrine regulatory factor that regulates chondrogenesis of mouse mesenchymal cells (Kim, J. S., Ryoo, Z. Y., and Chun, J. S. (2007) J. Biol. Chem. 282, 29359 -29367). In this previous work, we found that Cytl1 expression was very low in mesenchymal cells, increased dramatically during chondrogenesis, and decreased during hypertrophic maturation, both in vivo and in vitro. Moreover, exogenous addition or ectopic expression of Cytl1 caused chondrogenic differentiation of mouse limb bud mesenchymal cells. In the current study, we generated a Cytl1 knockout (Cytl1 ؊/؊ ) mouse to investigate the in vivo role of Cytl1. Although a number of regulatory factors have been identified, the precise regulatory mechanisms underlying chondrogenesis and cartilage and bone development remain to be elucidated. In permanent cartilage tissue, cartilage homeostasis is maintained by chondrocytes, which are a cell type unique to cartilage tissue. Cartilage homeostasis is disrupted in osteoarthritis (OA), leading to eventual cartilage destruction. OA is a progressive and degenerative disorder of the joint primarily characterized by articular cartilage destruction. A variety of potential OA-causing mechanisms have been proposed (5-7). Biophysical and biochemical factors, such as mechanical stress and proinflammatory cytokines, respectively, are responsible for disruption of cartilage homeostasis and initiation of the catabolic pathway. This, in turn, activates intracellular pathways in chondrocytes that lead to the production of pro-inflammatory cytokines, inflammation, degradation of the ECM by matrixdegrading enzymes, and cessation of ECM synthesis via dedifferentiation and apoptosis of chondrocytes (5-7). Deletion of theWe have previously shown that cytokine-like 1 (Cytl1) is a novel autocrine regulatory factor involved in chondrogenesis of mouse mesenchymal cells in vitro (8). CYTL1 was originally cloned as a functionally unknown cytokine candidate from human bone marrow and cord blood mononuclear cells bearing the CD34 surface marker (9). The CYTL1 protein contains four ␣-helices and six conserved cysteine residues, which may form intra-disulfide bonds to yield a globular structure, a common structural characteristic of cytokines. CYTL1 also contains an N-terminal secretory signal peptide, and its secretion is associated with post-translational modifications, although the nature of these modifications remains to be established (8

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Submitted：April 18, 2016 1 st Revision：September 5, 2016 Accepted：September 8, 2016 * 서울대학교 경영대학 박사과정 수료, 주저자 ** 서울대학교 경영대학 석사과정 졸업, 교신저자 *** 서울대학교 경영대학 교수 The purpose of the study is to derive success factors of B2C reverse auction business model, a business model contributes to the recent innovative practices in e-commerce and service sector. Electronic reverse auction has been traditionally used to ensure the procurement convenience and purchasing efficiency in B2B or B2G settings, however, e-RA is now expanding its basis toward B2C commerce industry along the huge success of an online e-RA travel service provider Priceline.com. Recently, B2C e-RA business model is getting the spotlight in the Korean venture industry with a variety of startups in diverse areas.However, e-RA does not work perfect in all kinds of trade settings. Therefore, we conducted a multiple case study to find out the success factors of B2C business model as follows : First, large supplier basis is an important factor that constructs a quasi-perfect competition environment. Second, the high online and mobile accessibility or ereadiness of Korean consumers was also a critical aspect of the success of e-RA. Lastly, e-RA performs best when the supplier switching cost is low and the trading occurs infrequently.