A growth inhibitor implicated in the growth arrest of human fibroblasts.

When quiescent human fibroblasts are induced to divide, the sugar composition of a growth inhibitory glycoprotein is modified. The kinetics of the incorporation of glucosamine in the growth inhibitor follows the kinetics of cell growth. It increases as cells approach quiescence and declines when cells initiate proliferation. The results suggest that the modification of the sugar composition of this glycoprotein is coupled with the variation of its inhibitory potential and this way to the initiation and the arrest of cell division.