To clarify the multiple functionality of connective tissue growth factor (CTGF), we examined the effects of nascent CTGF within the cell by transient expression. Tn Cos-7 cells, expression of human CTGF induced an altered cell morphology, It was associated with an increased cellular DNA content and loose attachment, indicating the cells mere in G2/M phase. Overexpression of CTGF did not induce cell growth, whereas recombinant CTGF efficiently stimulated the proliferation extracellularly, These results indicate that intracellular CTGF may act as an antimitotic agent, thus it should also be noted that nascent CTGF was found to accumulate around the central mitotic machinery. (C) 2000 Federation of European Biochemical Societies.