AIM:To establish FL- CROC -1 - cell line in which CROC -1 gene expression was blocked and study the role of CROC -1 gene in cell growth. METHODS:The appropriate length cDNA fragment of the recently identified human gene CROC -1 which encodes ubiquitin-conjugating enzyme like protein(Ubc-like protein) was cloned into the reconstructed eukaryotic expression vector pMAMneo-amp - by antisense strategy. The recombinant plasmid which can express CROC -1 antisense RNA was selected by restriction enzyme map analysis. The antisense expression recombinant plasmid pMAM-anti CROC -1 was then transfected into human amnion FL cells by a modified calcium phosphate-mediated transfection procedure and selected with MEM medium containing 400 ?g/mL geneticin. Finally ,the growth rate of the G418 resistant FL- CROC -1 - cell line was determined. RESULTS:When the antisense inhibition of CROC -1 gene expression was induced by dexamethasone, the growth rate of the FL- CROC -1 - cell line was obviously slower as compared with that of the control FL cell and FL-MAMneo cell which was established by transfection of plasmid pMAMneo-amp - ( P