RECK(reversion-inducing cysteine-rich protein with Kazal motifs) encodes a membrane-anchored glycoprotein of about 110 kDa with multiple epidermal growth factor-like repeat, four N-glycosylation sites and three Kazal-like domains. RECK functions as a tumor suppressor gene which may inhibit the release and activation of MMP-2 and MMP-9. Previous studies indicated that RECK-mediated suppression of tumor cell invasion is regulated by glycosylation of RECK in human tumor cell lines. However, the anti-cancer action of other functional domains of RECK have not been studied. In the study, We investigated the effects of different functional domains of RECK protein on the invasion of tumor cell lines and on the activation of matrix metalloproteinase. We constructed bacterial expression vector and secretory mammalian expression vector which could produce full-length, Kazal-like motifs 1~3, Kazal-like motifs 2~3 and CKM5 polypeptides. Recombinant proteins were purified and used for treatment of human lung cancer cell lines. We found that treatment of K23 and RECK recombinant proteins resulted in suppression of invasive ability and MMP activity. Moreover,K23 and RECK proteins were found to inhibit the secretion of matrix metallo- protease-9 (MMP-9). K23 also formed a complex with MMP-9 and inhibited its proteolytic activity noncompetitively. Experimental metastasis assay revealed that there were fewer tumor nodule formation in the lungs injected with A549 cells stably expressing K23 than control vector. Thus, these findings indicate that the K23 domain of RECK functions as an inhibitor of tumor invasion and metastasis.